Congenital adrenal hyperplasia ( CAH ) is a collection of autosomal recessive disorders marked by disrupted cortisol production. It arises from a deficiency in one of the five enzymes necessary for synthesis of cortisol in the adrenal cortex . These disorders often involve abnormal production of hormones like glucocorticoids , mineralocorticoids , or sex steroids , potentially affecting the development of primary or secondary sex characteristics in some affected infants , children, or adults. It is among the most prevalent autosomal recessive disorders in humans. Types CAH manifests in different forms. Each form's clinical presentation varies significantly based on the specific enzyme defect, precursor retention, and product deficiency. Classical forms are evident in infancy, while nonclassical forms emerge in late childhood. Classic CAH can be further divided into salt-wasting and simple-virilizing forms, depending on the presence or absence of mineralocorticoid deficiency. However, this classification is often clinically insignificant since all patients experience some salt loss, and symptoms may overlap. Classic Salt-wasting In 75% of severe enzyme deficiency cases, inadequate aldosterone production can cause salt wasting, growth failure, and potentially life-threatening hypovolemia and shock. A missed diagnosis of salt-loss CAH is linked to increased risk of early neonatal morbidity and mortality. Simple-virilizing The primary feature of CAH in newborn females is abnormal external genitalia development, with varying degrees of virilization . Clinical practice guidelines recommend CAH evaluation for newborns with bilateral inaccessible gonads. If virilizing CAH is not identified and treated, both boys and girls may experience rapid postnatal growth and virilization. Nonclassic Besides the salt-wasting and simple-virilizing forms diagnosed in infancy, there is a mild or "nonclassic" form, characterized by varying degrees of postnatal androgen excess, sometimes asymptomatic. The nonclassic form may become apparent in late childhood, leading to signs of hyperandrogenism such as accelerated growth, acne , hirsutism, premature pubarche, menstrual irregularities, and secondary polycystic ovary syndrome . In adult males, early balding and infertility may indicate the diagnosis. The nonclassic form involves mild subclinical impairment of cortisol synthesis, with usually normal serum cortisol levels. Signs and Symptoms The symptoms of CAH differ based on the type of CAH and the patient's gender. Possible symptoms include: Due to insufficient mineralocorticoids : Vomiting caused by salt-wasting , which can lead to dehydration and potentially death Due to excessive androgens: Severe virilization may result in clitoromegaly (enlarged clitoris) resembling a phallic structure. Ambiguous genitalia can occur in some infants, making it challenging to initially determine the external genitalia as "male" or "female". Early appearance of pubic hair and rapid growth during childhood. Precocious puberty or absence of puberty development ( sexual infantilism : absent or delayed puberty ) Excessive facial hair , virilization, and/or menstrual irregularity during adolescence Infertility due to anovulation Shallow vagina Due to insufficient androgens and estrogens: Undervirilization in XY males can lead to an apparent vulva . Ambiguous genitalia in XY males with 3β-hydroxysteroid dehydrogenase deficiency ( 3β-HSD2D ). In females, hypogonadism may result in sexual infantilism or atypical pubertal development, infertility , and other reproductive system issues. Genetics CAH arises from mutations in genes that code for enzymes involved in the biochemical processes of producing mineralocorticoids , glucocorticoids , or sex steroids from cholesterol within the adrenal glands ( steroidogenesis ). Each CAH type is linked to a particular defective gene. The most prevalent form (95% of cases) involves the gene for 21-hydroxylase , located at 6p21.3 within the HLA complex; 21-hydroxylase deficiency is due to a specific mutation with two closely similar copies in sequence, comprising an active gene ( CYP21A2 ) and an inactive pseudogene ( CYP21A1P ). Mutant alleles result from recombination between the active and pseudogenes (gene conversion). Approximately 5% of CAH cases are caused by defects in the gene for 11β-hydroxylase , leading to 11β-hydroxylase deficiency . Other, rarer CAH forms are due to mutations in genes such as HSD3B2 (3β-hydroxysteroid dehydrogenase 2), CYP17A1 (17α-hydroxylase/17,20-lyase), CYP11A1 (P450scc; cholesterol side-chain cleavage enzyme), STAR ( steroidogenic acute regulatory protein ; StAR), CYB5A ( cytochrome b5 ), and CYPOR ( cytochrome P450 oxidoreductase ; POR). Expressivity Additional variability is introduced by the level of enzyme inefficiency caused by the specific alleles present in each patient. Some alleles lead to more severe enzyme inefficiency. Generally, severe inefficiency results in changes in the fetus and issues during prenatal or perinatal life. Milder inefficiency is often linked to excessive or deficient sex hormone effects during childhood or adolescence, while the mildest CAH forms affect ovulation and fertility in adults. Diagnosis Clinical evaluation Female infants with classic CAH exhibit ambiguous genitalia due to high androgen exposure in utero . CAH caused by 21-hydroxylase deficiency is the leading cause of ambiguous genitalia in genotypically normal female infants (46XX). Less severely affected females may show early pubarche . Young women might experience symptoms of polycystic ovarian syndrome ( oligomenorrhea , polycystic ovaries, hirsutism ). Males with classic CAH typically show no signs at birth. Some may display hyperpigmentation , due to co-secretion with melanocyte-stimulating hormone, and potential penile enlargement. The diagnosis age for males with CAH varies based on the severity of aldosterone deficiency. Boys with salt-wasting disease present early with hyponatremia and hypovolemia symptoms. Boys without salt-wasting present later with virilization signs. In less common forms of CAH, males are undermasculinized, and females usually show no signs or symptoms at birth. Laboratory studies Genetic analysis can confirm a CAH diagnosis, but it's not necessary when classic clinical and laboratory findings are present. In classic 21-hydroxylase deficiency, laboratory tests reveal: Hypoglycemia (due to hypocortisolism) - Cortisol functions to increase blood glucose levels through mechanisms such as (a) stimulating gluconeogenesis in the liver, (b) promoting glycogenolysis, and (c) preventing glucose from leaving the bloodstream by downregulating GLUT-4 receptors. When cortisol is deficient, these processes are effectively reversed. Although compensatory mechanisms exist to mitigate hypocortisolism's impact, they are limited, resulting in hypoglycemia. Hyponatremia (due to hypoaldosteronism) - Aldosterone, the end product of the renin-angiotensin-aldosterone system, regulates blood pressure by increasing sodium retention in exchange for potassium. A lack of aldosterone leads to hyperkalemia and hyponatremia. This distinguishes it from 11-hydroxylase deficiency, where excess 11-deoxycorticosterone, with weak mineralocorticoid activity, retains sodium at potassium's expense, preventing salt wasting and causing hypertension/water retention and sometimes hypokalemia. Hyperkalemia (due to hypoaldosteronism) Elevated 17α-hydroxyprogesterone Classic 21-hydroxylase deficiency typically results in 17α-hydroxyprogesterone blood levels >242 nmol/L. For comparison, a full-term infant at three days of age should have <3 nmol/L. Neonatal screening programs often have specific reference ranges by weight and gestational age, as high levels may occur in premature infants without CAH. Salt-wasting patients usually have higher 17α-hydroxyprogesterone levels than non-salt-wasting patients. In mild cases, 17α-hydroxyprogesterone may not be elevated in a random blood sample but will rise during a corticotropin stimulation test . Classification Cortisol, an adrenal steroid hormone, is essential for normal endocrine function, with production beginning in the second month of fetal life. Poor cortisol production is a hallmark of most CAH forms. Inefficient cortisol production results in rising ACTH levels, as cortisol inhibits ACTH production. Increased ACTH stimulation causes overgrowth ( hyperplasia ) and overactivity of the adrenal cortex's steroid-producing cells. The defects causing adrenal hyperplasia are congenital (present at birth). Cortisol deficiency in CAH is usually partial and not the most serious issue. Cortisol synthesis shares steps with mineralocorticoid synthesis like aldosterone, androgens like testosterone , and estrogens like estradiol . Excessive or deficient production of these hormones causes the most significant problems in CAH. Specific enzyme inefficiencies are linked to characteristic patterns of mineralocorticoid or sex steroid over- or underproduction. Since the 1960s, most endocrinologists have used traditional names for CAH forms, which correspond to deficient enzyme activity. In the 1980s, as enzyme structures and genes were identified, most enzymes were found to be cytochrome P450 oxidases and renamed accordingly. Some reactions involve multiple enzymes, while a single enzyme may mediate multiple reactions. Variation exists in different tissues and mammalian species. In all its forms, congenital adrenal hyperplasia due to 21-hydroxylase deficiency accounts for about 95% of diagnosed CAH cases. Unless another specific enzyme is mentioned, "CAH" usually refers to 21-hydroxylase deficiency. (The terms "salt-wasting CAH" and "simple virilizing CAH" typically refer to subtypes of this condition.) CAH due to deficiencies in enzymes other than 21-hydroxylase presents similar management challenges as 21-hydroxylase deficiency, but some involve mineralocorticoid excess or sex steroid deficiency. Common medical term % OMIM Enzyme(s) Locus Substrate(s) Product(s) Mineralocorticoids Androgens 21-Hydroxylase CAH 95% 201910 P450c21 6p21.3 17-OH-Progesterone→ Progesterone→ 11-Deoxycortisol DOC ↓ ↑ 11β-Hydroxylase CAH 5% 202010 P450c11β 8q21-22 11-Deoxycortisol→ DOC→ Cortisol Corticosterone ↑ ↑ 3β-HSD CAH Very rare 201810 3βHSD2 1p13 Pregnenolone→ 17-OH-Pregnenolone→ DHEA→ Progesterone 17-OH-Progesterone Androstenedione ↓ ↓ 17α-Hydroxylase CAH Very rare 202110 CYP17A1 10q24.3 Pregnenolone→ Progesterone→ 17-OH-Pregnenolone→ 17-OH-Pregnenolone 17-OH-Progesterone DHEA ↑ ↓ Lipoid CAH (20,22-desmolase) Very rare 201710 StAR P450scc 8p11.2 15q23-q24 Transport of cholesterol Cholesterol→ Into mitochondria Pregnenolone ↓ ↓ Screening In the United States and over 40 other countries, newborns are routinely screened for 21-hydroxylase CAH at birth. This screening identifies elevated levels of 17α-hydroxyprogesterone (17-OHP). High levels of 17-OHP allow for early detection of CAH, enabling newborns to begin medication early and lead relatively normal lives. However, the screening process has a high rate of false positives. In one study, CAH screening showed the lowest positive predictive value (111 true-positive cases out of 20,647 abnormal screening results over two years, or 0.53%, compared to 6.36% for biotinidase deficiency, 1.84% for congenital hypothyroidism, 0.56% for classic galactosemia, and 2.9% for phenylketonuria). This suggests that 200 unaffected newborns required clinical and laboratory follow-up for each true case of CAH. In 2020, Wael AbdAlmageed from the USC Information Sciences Institute and Mimi Kim from USC's Keck School Of Medicine conducted a joint study using deep learning technology to examine the facial morphology and features of CAH patients compared to controls. In this cross-sectional study of 102 CAH patients and 144 control participants, deep learning methods achieved a mean area under the receiver operating characteristic curve of 92% for predicting CAH from facial images. Facial features differentiated CAH patients from controls, with analyses showing the nose and upper face as most contributory. These findings indicate that facial morphologic features, as analyzed by deep neural networks, can serve as a phenotypic biomarker for predicting CAH. Treatment The clinical manifestations of each CAH form are distinct and largely depend on the specific enzyme defects, precursor retention, and defective products. The therapeutic objective of CAH is to replenish deficient adrenal hormones and suppress excess precursors. Treatment for all forms of CAH may include: Administering sufficient glucocorticoid to reduce hyperplasia and overproduction of androgens or mineralocorticoids Providing replacement mineralocorticoid and additional salt if there is a deficiency Supplying replacement testosterone or estrogens during puberty if deficient Additional treatments to optimize growth by delaying puberty or bone maturation If CAH is due to a 21-hydroxylase enzyme deficiency, treatment aims to normalize androstenedione levels, while normalization of 17α-hydroxyprogesterone indicates overtreatment. Monitoring involves measuring androstenedione and 17α-hydroxyprogesterone levels in blood or saliva. Crinecerfont (Crenessity) received approval for medical use in the United States in December 2024.

Cycle syncing involves modifying lifestyle habits, such as diet and exercise, to align with the various stages of the menstrual cycle . This approach can aid in managing symptoms, enhancing energy levels, and potentially boosting overall well-being.  The Four Main Phases of the Menstrual Cycle:  Menstrual Phase (Days 1-7): Hormone levels are at their lowest, resulting in generally low energy. It is advisable to rest, engage in low-impact activities like yoga or walking, and consume nourishing foods.  Follicular Phase (Days 8-13): As estrogen begins to rise, energy and focus increase. This phase is ideal for more intense workouts and social activities.  Ovulation Phase (Days 14-15): With peaks in estrogen and testosterone, energy levels are high. This is an excellent time to challenge yourself with workouts and activities.  Luteal Phase (Days 16-28): As progesterone production increases, mood swings, fatigue, and bloating may occur. Rest, gentle exercises, and foods that support progesterone levels are recommended.  The Cycle Syncing Graph. How to Cycle Sync: Track your cycle: Observe your physical and emotional changes throughout the month.  Adjust your diet: Focus on nutrient-rich, whole foods, and consider foods that may alleviate specific symptoms, like dark chocolate for cramps.  Tailor your exercise: Modify workout intensity and type according to your energy levels and the phase of your cycle.  Practice self-care: During menstruation, prioritize rest and relaxation. In the follicular and ovulation phases, engage in energizing activities. In the luteal phase, focus on self-care and gentle movement.

Complete androgen insensitivity syndrome ( CAIS ) is a type of AIS condition where the cell cannot respond to androgens . This insensitivity is clinically relevant when individuals are exposed to significant testosterone levels during their lifetime. The cell's unresponsiveness to androgenic hormones hinders the masculinization of male genitalia in the developing fetus and the development of male secondary sexual characteristics during puberty , yet it permits normal female genital and sexual development in affected individuals. All human fetuses initially develop similarly, with both the Müllerian duct system (female) and the Wolffian duct system (male) forming. Sex differentiation starts with the gonads , which become ovaries in XX individuals, and typically form testicles in XY individuals (including those with CAIS) due to the Y chromosome. In the seventh week of gestation , the bodies of non-CAIS XY individuals begin masculinization: the Wolffian duct system is promoted, and the Müllerian duct system is suppressed (the opposite occurs in typically developing females). This process is initiated by androgens from the testicles. The bodies of unaffected XY individuals masculinize by enlarging the genital tubercle into a penis , which becomes the clitoris in females, while the area that becomes labia in females fuses to form the scrotum in males (where the testicles will later descend). XY individuals with CAIS develop a normal external female habitus , despite having a Y chromosome, but internally, they lack a uterus , and the vaginal cavity is shallow, while the gonads, which differentiated into testes due to the Y chromosome, remain undescended. This leads to infertility in CAIS individuals and increases the risk of gonadal cancer later in life. CAIS is one of three types of androgen insensitivity syndrome (AIS), categorized by the degree of genital masculinization : complete androgen insensitivity syndrome (CAIS) when external genitalia appear typically female, mild androgen insensitivity syndrome (MAIS) when they appear typically male, and partial androgen insensitivity syndrome (PAIS) when the external genitalia are partially but not fully masculinized. Androgen insensitivity syndrome is the most common cause of 46, XY undermasculinization . Signs and Symptoms Physical Individuals with complete androgen insensitivity syndrome (grades 6 and 7 on the Quigley scale ) are born with an external female phenotype and show no signs of genital masculinization, despite having a 46,XY karyotype . CAIS is typically identified during puberty , which may be slightly delayed but is otherwise normal except for the absence of menses and reduced or absent secondary terminal hair . Axillary hair (armpit hair) does not develop in one-third of cases. The vulva appears normal, though the labia and clitoris may be underdeveloped. Vaginal depth varies significantly in CAIS, often being shorter than average; a study of eight individuals with CAIS found the average vaginal depth to be 5.9 cm (compared to 11.1 ± 1.0 cm in unaffected women). In some extreme cases, the vagina is reported to be aplastic (resembling a "dimple"), though the exact frequency of this is unknown. The gonads in individuals with CAIS are testes ; during the embryonic stage of development , testes form through an androgen-independent process influenced by the SRY gene on the Y chromosome . They may be located intra-abdominally, at the internal inguinal ring , or may herniate into the labia majora , often leading to the condition's discovery. Testes in affected individuals have been found to be atrophic upon gonadectomy . The testosterone produced by the testes cannot be directly utilized due to the mutant androgen receptor characteristic of CAIS; instead, it is aromatized into estrogen , which effectively feminizes the body and results in the normal female phenotype seen in CAIS. However, up to 5% of individuals with CAIS do not have an AR mutation. The receptor is encoded by the AR gene located on the X chromosome at Xq11–12. At least 15 different mutations were known in 2003, all of which are recessive, making the condition follow X-linked recessive inheritance . Immature sperm cells in the testes do not mature beyond an early stage, as androgen sensitivity is necessary for spermatogenesis to complete. The risk of germ cell malignancy , once considered relatively high, is now thought to be approximately 2%. Wolffian structures (the epididymides , vasa deferentia , and seminal vesicles ) are usually absent, but will develop at least partially in about 30% of cases, depending on the mutation causing the CAIS. The prostate , like the external male genitalia , cannot masculinize in the absence of androgen receptor function, and thus remains in the female form . The Müllerian system typically regresses in the same manner as in unaffected male fetuses due to the anti-Müllerian hormone produced by the Sertoli cells of the testes. Therefore, individuals with CAIS, despite having a vagina due to androgen insensitivity, are born without fallopian tubes, a cervix , or a uterus, and the vagina ends in a "blind" pouch. Müllerian regression does not fully complete in some CAIS cases, leading to Müllerian "remnants". Although rare, a few cases of individuals diagnosed with CAIS having Müllerian structures have been reported. In one exceptional case, a 22-year-old with CAIS was found to have a cervix, uterus, and fallopian tubes. In an unrelated instance, an almost fully developed uterus was found in a 22-year-old adult with CAIS. Other subtle differences reported include slightly longer limbs and larger hands and feet due to a proportionally greater stature than unaffected women, larger teeth, minimal or no acne, well developed breasts , a higher incidence of meibomian gland dysfunction (such as dry eye syndromes and light sensitivity ), and dry skin and hair due to a lack of sebum production. Endocrine Several studies have documented hormone levels in gonadally intact individuals with CAIS. These levels are comparable to those found in males, characterized by elevated testosterone and relatively low estradiol . However, luteinizing hormone (LH) levels are higher, while sex hormone-binding globulin (SHBG) levels align more closely with those of females. Individuals with CAIS have low progesterone levels, similar to males. The production rates of testosterone, estradiol, and estrone are reported to be higher in gonadally intact individuals with CAIS than in men. Comorbidity All types of androgen insensitivity, including CAIS, are linked with infertility , although exceptions have been noted in mild and partial forms. CAIS is linked to a reduction in bone mineral density . Some suggest that the reduced bone mineral density observed in women with CAIS may be related to the timing of gonadectomy and insufficient estrogen supplementation . However, recent studies indicate that bone mineral density is similar whether gonadectomy occurs before or after puberty , and remains decreased despite estrogen supplementation, suggesting that the deficiency may be directly due to the role of androgens in bone mineralization . CAIS also carries a higher risk for gonadal tumors (e.g., germ cell malignancy) in adulthood if gonadectomy is not performed. The risk of malignant germ cell tumors in women with CAIS increases with age, estimated at 3.6% by age 25 and 33% by age 50. The occurrence of gonadal tumors in childhood is considered relatively low; a recent review of medical literature found only three cases of malignant germ cell tumors in prepubescent girls associated with CAIS in the last century. Some estimate the incidence of germ cell malignancy to be as low as 0.8% before puberty. Vaginal hypoplasia , a common finding in CAIS and some forms of PAIS, is linked with sexual difficulties, including challenges with vaginal penetration and dyspareunia . One study suggests that individuals with a DSD condition may be more susceptible to psychological challenges, partly due to parental attitudes and behaviors, recommending preventative long-term psychological counseling for both parents and affected individuals from the time of diagnosis. AIS does not appear to affect lifespan. Despite well-developed breasts in CAIS women, and for reasons not fully understood, breast cancer has never been reported in CAIS women and seems to be rare or nonexistent. Only one case of juvenile fibroadenoma has been documented. A few cases of breast cancer have been reported in individuals with partial androgen insensitivity syndrome . Diagnosis CAIS is typically not considered until menstruation does not occur at puberty, or an inguinal hernia appears before menarche . Up to 1–2% of prepubertal girls with an inguinal hernia may also have CAIS. CAIS or Swyer syndrome can be diagnosed in utero by comparing a karyotype obtained through amniocentesis with the fetus's external genitalia during a prenatal ultrasound . Many infants with CAIS do not undergo the typical neonatal testosterone surge, which can be used diagnostically by measuring baseline luteinizing hormone and testosterone levels, followed by a human chorionic gonadotropin (hCG) stimulation test. The primary differential diagnoses for CAIS include complete gonadal dysgenesis ( Swyer syndrome ) and Müllerian agenesis (Mayer-Rokitansky-Kuster-Hauser syndrome or MRKH). Both CAIS and Swyer syndrome are linked to a 46,XY karyotype , whereas MRKH is not; MRKH can be excluded by checking for a Y chromosome , which can be done through fluorescence in situ hybridization (FISH) analysis or a full karyotype. Swyer syndrome is characterized by the presence of a uterus, underdeveloped breasts, and shorter stature. CAIS is confirmed when androgen receptor (AR) gene sequencing identifies a mutation , although up to 5% of individuals with CAIS do not have an AR mutation. Until the 1990s, a CAIS diagnosis was often not disclosed to the affected person or their family. Currently, it is common practice to reveal the genotype at the time of diagnosis, especially when the individual is at least an adolescent. If the individual is a child or infant, the decision to disclose the diagnosis is typically made by the parents, often with the guidance of a psychologist. Management Currently, the management of AIS focuses on symptomatic management . There are no available methods to correct a defective androgen receptor protein caused by an AR gene mutation . Management strategies include sex assignment , genitoplasty , gonadectomy concerning tumor risk, hormone replacement therapy , as well as genetic and psychological counseling . Non-consensual interventions are still frequently performed, although awareness of the psychological trauma they may cause is increasing. Sex assignment and sexuality Most individuals with CAIS are raised as females. They are born with an external phenotype typical of females and are generally considered to be heterosexual with a female gender identity . However, some studies suggest that individuals with CAIS may have more diverse gender outcomes and a non-primarily heterosexual orientation compared to similar groups with MRKH syndrome and PCOS , challenging this belief. At least two case studies have noted a male gender identity in individuals with CAIS. Dilation therapy Most instances of vaginal hypoplasia related to CAIS can be treated with non-surgical pressure dilation techniques. The elastic nature of vaginal tissue, as shown by its capacity to adapt to the size differences between a tampon , a penis, and a baby's head, allows for dilation even when vaginal depth is significantly reduced. Treatment compliance is considered crucial for satisfactory outcomes. Dilation can also be accomplished through the Vecchietti procedure , which extends vaginal tissues into a functional vagina using a traction device anchored to the abdominal wall , subperitoneal sutures , and a mold placed against the vaginal dimple. Vaginal stretching occurs by daily increasing the tension on the sutures. The non-surgical pressure dilation method is currently recommended as the first option due to its non-invasive nature and high success rate. Vaginal dilation should not be performed before puberty . Gonadectomy Although it has often been advised that women with CAIS eventually undergo gonadectomy to reduce cancer risk, there are varying opinions on the necessity and timing of this procedure. The risk of malignant germ cell tumors in CAIS increases with age, estimated at 3.6% by age 25 and 33% by age 50. However, only three cases of malignant germ cell tumors in prepubescent girls with CAIS have been documented over the past century. The youngest of these was 14 years old. Individuals with CAIS naturally experience puberty through the aromatization of testosterone into estrogens. Thus, removing the gonads necessitates hormone replacement therapy . Gonadectomy is typically not advised before puberty to allow natural puberty to occur. Some individuals with CAIS may opt for testosterone HRT instead of estrogen. Studies indicate that testosterone is at least as effective as estrogen replacement therapy and may enhance certain aspects of well-being. If gonadectomy is done early, puberty must be induced artificially with gradually increasing doses of estrogen . If gonadectomy is performed later, puberty will occur naturally due to the aromatization of testosterone into estrogen . At least one organization, the Australasian Paediatric Endocrine Group, considers the cancer risk in CAIS low enough to advise against gonadectomy, though it cautions that the cancer risk remains higher than in the general population, and ongoing cancer monitoring is crucial. Some choose to perform gonadectomy if an inguinal hernia occurs. Estrogen replacement therapy is vital to prevent bone mineral density deficiencies later in life. Some individuals with CAIS may decide to keep their gonads. In this case, annual imaging of the gonads via MRI or ultrasound is recommended to monitor for malignancy. Diagnostic laparoscopy and biopsy should also be considered if imaging results are unclear. Hormone replacement therapy It has been suggested that higher-than-normal levels of estrogen might help mitigate the reduced bone mineral density linked to CAIS. Research has shown that women affected by CAIS who did not adhere to estrogen replacement therapy, or who experienced interruptions, faced a greater reduction in bone mineral density. Progestin replacement therapy is also rarely initiated. Androgen replacement has been noted to enhance well-being in individuals with CAIS who have undergone gonadectomy, although the exact mechanism for this benefit remains unclear. Counseling It is now uncommon to conceal a diagnosis of CAIS from the individual or their family. Parents of children with CAIS require significant support in planning and communicating the diagnosis to their child. For parents with young children, sharing this information is a continuous, collaborative process that needs a personalized approach, adapting as the child develops cognitively and psychologically . In all situations, consulting a psychologist with expertise in this area is advisable. Neovaginal construction Various surgical techniques have been created to construct a neovagina , though none are perfect. Surgical intervention should only be considered if non-surgical pressure dilation methods do not achieve satisfactory outcomes. Neovaginoplasty can be performed using skin grafts , segments of bowel , ileum , peritoneum , an absorbable adhesion barrier (Intercede, produced by Johnson & Johnson ), buccal mucosa , amnion , dura mater , or with the aid of vaginal stents/expanders . The success of these methods should be evaluated based on sexual function , rather than solely on vaginal length, as was previously the case. Ileal or cecal segments may pose challenges due to a shorter mesentery , which can cause tension on the neovagina, leading to stenosis . The sigmoid neovagina is believed to be self-lubricating, without the excessive mucus production associated with small bowel segments. Vaginoplasty may result in scarring at the introitus (the vaginal opening), necessitating further surgical correction. Vaginal dilators are needed post-surgery to prevent vaginal stenosis due to scarring. Inflatable vaginal stents are inserted deflated and then gently inflated. Other possible complications include injuries to the bladder and bowel. Annual examinations are necessary as neovaginoplasty carries a risk of carcinoma , although neovaginal carcinoma is rare. Neither neovaginoplasty nor vaginal dilation should be performed before puberty . Prognosis Individuals affected by this condition face challenges such as psychologically accepting the condition, issues with sexual function, and infertility. Long-term research shows that with proper medical and psychological care, those with CAIS can achieve satisfaction with their sexual function and psychosexual development. People with this condition can lead active lives and have a normal life expectancy. Epidemiology CAIS is estimated to occur in 1 in 20,400 to 1 in 99,000 individuals with a 46,XY karyotype. Nomenclature Historically, CAIS has been known by several other names in the literature, including testicular feminization [syndrome] (now outdated) and Morris syndrome. PAIS has also been called Reifenstein syndrome, which should not be confused with CAIS.

Campomelic dysplasia ( CMD ) is a genetic disorder marked by the bowing of long bones and various other skeletal and extraskeletal features. It can be fatal during the neonatal period due to respiratory insufficiency , but the severity of the condition varies, and a notable number of patients live into adulthood. The name comes from the Greek roots campo (or campto ), meaning bent, and melia , meaning limb. A unique aspect of the disorder is that up to two-thirds of affected 46,XY genotypic males exhibit a range of disorders of sexual development (DSD) and genital ambiguities or may even develop as normal phenotypic females, as seen in complete 46 XY sex reversal . An atypical form of the disease, lacking bowed limbs, is simply called acampomelic campomelic dysplasia (ACD) and occurs in about 10% of patients, especially those who survive the neonatal period. Signs and symptoms While the definitive presentation of the disease is a patient having bowed lower limbs and sex reversal in 46,XY males, other clinical criteria can be used for diagnosis in the absence of these traits. Patients may exhibit shortened and angulated lower limbs, a vertically oriented and narrow pelvis, an enlarged head, a small jaw, cleft palate, flat nasal bridge, low set ears, and club feet. Radiographs may reveal underdeveloped shoulder blades, dislocated hips, hypoplastic vertebral pedicles in the thoracic region, 11 pairs of ribs instead of 12, or cervical spine kyphosis, which are helpful diagnostic indicators. Respiratory distress may be due to an underdeveloped trachea that collapses on inhalation or insufficient rib cage development. Genetics CMD is often caused by chromosomal abnormalities in or around the SOX9 gene on the long arm of chromosome 17 , specifically at position 17q24, usually arising spontaneously or de novo mutations . Numerous single nucleotide variants in the SOX9 gene have been identified that cause some form of CMD. The SOX9 gene encodes a protein transcription factor that, when expressed during the embryonic stage, plays a crucial role in determining sexual characteristics and significantly influences skeletal development. When the SRY gene of the Y chromosome is expressed in human embryos, a cascade of gene interactions controlled by SOX9 begins, ultimately leading to male gender. Any mutation within the coding region of SOX9 can result in campomelic dysplasia, and 75% of reported mutations lead to sex reversal. Four major classes of heterozygous SOX9 mutations can cause CMD: amino acid substitutions in the HMG-box , truncations or frameshifts altering the C-terminal end, mutations at the splice junction, and chromosomal translocations . Additionally, mutations upstream of SOX9 can also cause CMD. Several researchers have identified cis-acting control elements upstream of SOX9 . Translocation breakpoints scattered over 1Mb proximal to SOX9 suggest an extended control region. The lack of correlation between specific genetic mutations and observed phenotype , particularly concerning sex reversal, clearly demonstrates the variable expressivity of the disease. Milder forms of the disease, seen in those who survive beyond the neonatal period and those with ACD, may be attributed to somatic mosaicism —especially for those with mutations within the SOX9 coding region . Chromosomal aberrations in the upstream control regions or residual activity of the mutant SOX9 protein might also contribute to the milder forms of the disease. Long-term survivors of CMD are significantly more likely to have translocation and inversion mutations upstream of SOX9 rather than mutations in the SOX9 coding region itself. Diagnosis In utero sonographic diagnosis is feasible when characteristic features such as bilateral bowed femurs and tibia, clubbed feet, prominent neck curvature, a bell-shaped chest, pelvic dilation, and/or a small jaw are evident. Radiographic techniques are typically employed postnatally and also rely on typical physical characteristics. However, bent bones are a nonspecific sign, and most fetuses with bent bones will have conditions other than campomelic dysplasia. Screening Genetic screening can be performed using comparative genomic hybridization (CGH) studies with DNA microarrays , and by PCR and sequencing of the entire SOX9 gene. Many different translocation breakpoints and related chromosomal aberrations have been identified in patients with CMD. Prognosis In over half of the cases, death occurs during the neonatal period due to respiratory distress , generally linked to a small chest size or inadequate development of the trachea and other upper airway structures. Among CMD survivors, skeletal malformations evolve over time, often resulting in worsening scoliosis or kyphosis , leading to a decreased trunk size relative to limb length. Neurological damage is also common, including spinal cord compression and deafness . Even among those who survive the prenatal period, CMD patients have shortened life spans due to lifelong respiratory issues. Patients with ambiguous genitalia or sex reversal at birth continue to experience these conditions and are either sterile or have reduced fertility. Epidemiology Campomelic dysplasia has an incidence rate of 0.05-0.09 per 10,000 live births.

A bifid penis (or double penis ) is a rare congenital defect where two genital tubercles develop. Many species of male marsupials have a naturally bifurcated penis, with left and right prongs that they insert into multiple vaginal canals simultaneously.

Barber-Say syndrome (BSS) is an extremely rare congenital disorder characterized by excessive hair growth ( hypertrichosis ), delicate ( atrophic ) skin, eyelid abnormalities ( ectropion ), and an unusually wide mouth ( macrostomia ). Barber-Say syndrome shares phenotypic similarities with Ablepharon macrostomia syndrome , which is also linked to dominant mutations in TWIST2 . Signs and Symptoms Pronounced hypertrichosis, particularly on the back Skin irregularities, including hyperlaxity and excess Facial abnormalities, such as macrostomia Eyelid abnormalities Unusual and low-positioned ears Bulbous nasal tip with underdeveloped alae nasi Low frontal hairline Genetics Several instances of parent-to-child transmission suggest that Barber-Say syndrome follows an autosomal dominant inheritance pattern. Exome sequencing and expression research have identified that BSS results from mutations in the TWIST2 gene, impacting a highly conserved residue of TWIST2 (twist-related protein 2). TWIST2 is a basic helix-loop-helix transcription factor that binds to E-box DNA motifs (5'-CANNTG-3') as a heterodimer and suppresses transcriptional activation. Since TWIST2 is involved in mesenchymal stem cell differentiation and prevents premature or misplaced osteoblast differentiation, mutations in TWIST2 that impair these functions by altering DNA-binding activity could account for many BSS phenotypes. Diagnosis Barber-Say Syndrome is a rare genetic disorder characterized by a range of symptoms. The diagnosis typically involves the following steps: Clinical Evaluation Medical History: Gathering information about the patient's symptoms, family history, and any developmental milestones. - Physical Examination: Assessing physical features and any associated anomalies. Genetic Testing Next-Generation Sequencing: This can identify mutations in the genes associated with Barber-Say Syndrome, primarily in the KMT2A gene. - Targeted Mutation Analysis: If a specific mutation is known in the family, testing can focus on that mutation. Imaging Studies MRI or CT Scans: These may be used to assess any structural abnormalities in the brain or other organs. Multidisciplinary Approach Consultations: Involvement of specialists such as geneticists, neurologists, and developmental pediatricians for comprehensive evaluation. Exclusion of Other Conditions Differential Diagnosis: Ensuring that symptoms are not attributed to other syndromes or genetic disorders. Early diagnosis is crucial for management and support for individuals with Barber-Say Syndrome. Treatment Barber Say syndrome, a rare genetic disorder characterized by various physical and developmental symptoms, requires a multidisciplinary approach for management. The treatment is generally focused on alleviating symptoms and improving the quality of life. Here are some common treatment options: 1. Medical Management Regular Monitoring: Regular check-ups with healthcare professionals to monitor growth, development, and any associated health issues. Medications: Depending on symptoms, medications may be prescribed to manage specific issues such as seizures, if present. 2. Physical Therapy Rehabilitation: Physical therapy can help improve motor skills and coordination, addressing any developmental delays. 3. Occupational Therapy Skill Development: Occupational therapy may assist in developing daily living skills and enhancing independence. 4. Speech Therapy Communication Skills: Speech therapy can help improve communication abilities, which may be affected in individuals. Epidemiology Barber Say syndrome occurs in fewer than 1 in 1,000,000 individuals. By 2017, only 15 cases had been documented in the literature.

Aromatase excess syndrome ( AES or AEXS ) is a rarely diagnosed genetic and endocrine syndrome characterized by an overexpression of aromatase , the enzyme responsible for the biosynthesis of estrogen sex hormones from androgens , leading to high levels of circulating estrogens and symptoms of hyperestrogenism . It affects both sexes , causing marked or complete phenotypical feminization in males (excluding the genitalia ; i.e., no ambiguous genitalia) and hyperfeminization in females . To date, 30 males and 8 females with AEXS have been documented among 15 and 7 families, respectively, in the medical literature . Signs and symptoms Physiological abnormalities include significant overexpression of aromatase and elevated estrogen levels, such as estrone and estradiol , with a high rate of peripheral androgen-to-estrogen conversion. One study found cellular aromatase mRNA expression to be at least 10 times higher in a female patient compared to controls, and the estradiol/ testosterone ratio after testosterone injection in a male patient was 100 times greater than controls. Another study showed androstenedione , testosterone, and dihydrotestosterone (DHT) to be low or normal in males, with very low follicle-stimulating hormone (FSH) levels due to estrogen's antigonadotropic effects, while luteinizing hormone (LH) levels were normal. A recent review noted elevated estrone levels in 94% of patients, while estradiol was elevated in 48%. Estrone is the main elevated estrogen. Over half of patients had low to subnormal androstenedione and testosterone levels, with the estradiol to testosterone ratio >10 in 75% of cases. FSH levels are consistently low, and LH levels are low to normal. Gynecomastia has been noted in patients with normal estradiol levels, possibly due to in situ conversion of adrenal androgens into estrone and estradiol in breast tissue, where aromatase activity might be high. AEXS symptoms in males include heterosexual precocity ( precocious puberty with inappropriate secondary sexual characteristics ), severe prepubertal or peripubertal gynecomastia (breast development), high-pitched voice , sparse facial hair , hypogonadism , oligozoospermia , small testes , micropenis , advanced bone maturation , early peak height velocity , and short final stature due to early epiphyseal closure . Gynecomastia is present in 100% of cases, with 20 of 30 males opting for mastectomy . In females, AEXS symptoms include isosexual precocity , macromastia , enlarged uterus, menstrual irregularities , accelerated bone maturation, and short final height. Of seven females documented, three had macromastia. Pubertal breast hypertrophy has been noted in two young girls. Fertility , while often affected, does not always prevent sexual reproduction , as evidenced by vertical transmission of the condition by both sexes. Cause The exact cause of AEXS is unclear, but it is linked to inheritable , autosomal dominant genetic mutations in CYP19A1 , the gene encoding aromatase. Different mutations lead to varying symptom severity, such as mild to severe gynecomastia. For instance, duplications cause mild gynecomastia, while deletions leading to chimeric genes result in moderate or severe gynecomastia. Diagnosis Genetic testing is available to identify CYP19A1 variants associated with AEXS. The National Institutes of Health provides a list. Treatment Effective treatments for AEXS include aromatase inhibitors and gonadotropin-releasing hormone analogues for both sexes, androgen replacement therapy with non-aromatizable androgens like DHT in males, and progestogens to suppress estrogen levels in females. Male patients often seek bilateral mastectomy , while females may choose breast reduction if necessary. Although medical treatment for AEXS is not mandatory, it is advised to prevent complications like excessively large breasts, fertility issues, and increased risks of endometriosis and estrogen-dependent cancers such as breast and endometrial cancers later in life. A case of male breast cancer has been reported.

Aromatase deficiency is an uncommon condition marked by very low or absent levels of the enzyme aromatase activity in the body. It is an autosomal recessive disorder caused by various mutations in the CYP19 (P450arom) gene, which can result in ambiguous genitalia and delayed puberty in females, continued growth into adulthood, and osteoporosis in males, as well as virilization in pregnant mothers. As of 2020, fewer than 15 cases have been documented in genetically male individuals and at least 30 cases in genetically female individuals. Signs and symptoms The deficiency leads to the virilization of XX fetuses. Symptoms typically emerge during adolescence or early adulthood. The absence of estrogen results in primary amenorrhea and increased height. The greater than expected height occurs because estrogen usually causes the fusion of the epiphyseal growth plates in the bones, and without it, the patient continues to grow. The gonadotropins LH and FSH are both elevated, and patients exhibit polycystic ovaries . Additionally, the low estrogen levels increase the risk of osteoporosis . Female After birth, female infants often show ambiguous genitalia, including labioscrotal fusion, clitoromegaly , and phallic genitalia. Hyperandrogenism is present at birth, along with low estrogen levels in the blood. However, they have normal internal female genitalia. Documented cases have shown Prader scale ratings between II and V, with most classified as IV (11 out of 23 cases) or III (7 out of 23 cases). Some 46,XX individuals are assigned male at birth due to sufficiently virilized genitalia, and a male gender identity persisted in some of these cases. During puberty, progressive signs of virilization, such as increased body hair, can be observed, along with puberty failure due to the lack of estradiol action. The disruption of the LHRH-LH/FSH axis results in delayed bone age without a growth spurt. In adulthood, symptoms include virilization, absence of breast development, primary amenorrhea , infertility, and multicystic ovaries. Other symptoms include hypergonadotropic hypogonadism , polycystic ovaries , hypoplastic ovaries, and tall stature. Male Symptoms typically appear in adulthood: Tall stature, osteopenia , osteoporosis , Type II Diabetes , hyperinsulinemia , acanthosis nigricans , lipid metabolism disorders, and impaired liver function. During pregnancy During pregnancy, a baby with Aromatase Deficiency can cause the mother to become virilized, leading to a deeper voice, cystic acne, excessive hair growth, cliteromegaly , and hirsutism . The mother also experiences increased circulating testosterone levels. However, these symptoms usually subside after childbirth. Complications Pregnant mother Aromatase is an enzyme that synthesizes estrone (E1) and estradiol (E2) from Androstenedione and Testosterone respectively. During pregnancy, the placenta , which is fetal tissue, produces large amounts of intermediates in the biosynthesis of estrogens, androstenedione and testosterone , but cannot convert them to estrogens due to the lack of aromatase. The accumulated androgen levels in the mother can rise up to 100 times higher than normal, leading to virilization of both the mother and the fetus. The mother may experience cystic acne, voice deepening, and hirsutism, but these symptoms typically resolve after delivery. If the fetus is male, it will develop normal male genitalia and grow normally, showing secondary male sexual characteristics. If the fetus is female, it will be born with ambiguous genitalia, such as labioscrotal fusion and a significantly enlarged phallus . Female Females lacking aromatase cannot produce estrone or estradiol, leading to a significant buildup of androgens in the blood. This disrupts the LHRH-LH/FSH axis, potentially causing polycystic ovaries in adulthood. Without estrogen, high levels of circulating LH and FSH result in hypergonadotropic hypogonadism. During adolescence, females begin to exhibit virilization and hair growth in various areas, but they cannot menstruate without estradiol, leading to primary amenorrhea, clitoromegaly, and lack of breast development. Puberty does not progress, resulting in an absence of growth spurts and delayed bone age. Without intervention, the excess androgens can lead to polycystic ovary development. Male Males with aromatase deficiency grow normally into adulthood. However, the very low circulating estrogen levels (<7 pg/mL) cause elevated FSH and LH levels in the blood. High androgen levels do not promote skeletal muscle growth harmoniously like estrogen, resulting in a eunuchoid body habitus. These individuals are typically tall and continue linear bone growth into adulthood. Without estrogen, epiphyseal plates do not fuse properly, allowing continuous height increase. Estrogen is crucial for bone homeostasis, and its deficiency leads to osteopenia and osteoporosis in the lumbar spine and cortical bone. Estrogen may also be linked to abnormal lipid profiles and hyperinsulinemia in men, though the exact mechanism is unclear. Cause Gene Mutation Aromatase deficiency is an autosomal recessive condition, with most mutations occurring in the highly conserved regions of the gene. Both homozygous and heterozygous mutations have been found at various locations on the exon of the P450 arom (CYP19) gene on chromosome 15p21.1. Additionally, mutations in cytochrome P450 oxidoreductase (POR), necessary for aromatase's enzymatic activity, can also cause aromatase deficiency. Diagnosis A fetus may be suspected of having aromatase deficiency if the pregnant mother shows signs of virilization. A female infant can be diagnosed physically due to abnormal genitalia and hormonal blood tests. The diagnosis is considered for any virilized 46,XX child when congenital adrenal hyperplasia is ruled out. In males, the condition might be suspected in late teens or twenties if they exhibit continued linear growth and bone pain. Extremely low estrogen levels and high androgens are diagnostic markers for aromatase deficiency in both genders. Testosterone levels in the urine may be normal or elevated. Treatment In males, transdermal estradiol replacement facilitates epiphyseal plates closure, enhances bone density, promotes skeletal maturation, normalizes FSH and LH levels, and reduces insulin blood concentration. In females, hormonal replacement therapy, such as cyclic oral therapy with conjugated estrogen, results in breast development, menses, pubertal growth spurts, resolution of ovarian cysts, suppression of elevated FSH and LH levels in the blood, and proper bone growth. Ambiguous genitalia, clitoromegaly, and ovarian cysts can be surgically removed (provided it is not illegal ).

Aphallia is a congenital malformation where the phallus ( penis or clitoris ) is missing. In males, it is also referred to as penile agenesis . The term originates from Ancient Greek a- meaning 'not' and phallos meaning 'penis'. It is categorized as a disorder of sex development . Causes The cause of aphallia remains unknown. It is not associated with insufficient hormone levels or activity, but rather with the failure of the fetal genital tubercle to develop between 3 and 6 weeks post-conception. In affected children, the urethra opens on the perineum . Diagnosis Aphallia is typically diagnosed at birth by observing the usually ambiguous genital area. Treatment Other congenital anomalies such as cryptorchidism , renal agenesis/dysplasia, and musculoskeletal and cardiopulmonary anomalies are common (in over 50% of cases), necessitating an evaluation for internal anomalies. Although aphallia can occur in any body type, it poses a greater challenge for individuals with testes. Historically, it has sometimes been a reason to assign and rear a male infant as a girl, based on the outdated 1950s theory that gender as a social construct is purely nurture-based, allowing a child to be raised as either gender. Many advocacy groups strongly oppose coercive genital reassignment and advocate for leaving infants' genitals intact. The nurture theory has largely been abandoned, as attempts to rear children this way have not resulted in successful transitions. Current consensus recommends male gender assignment. Recent advancements in surgical phalloplasty techniques offer additional options for those interested in surgery. Incidence Aphallia, or the absence of the penis, is an extremely rare congenital anomaly, with an estimated incidence of 1 in 10,000,000 births. It is rare, with only about 60 cases reported by 1989 and 75 by 2005. However, due to the stigma associated with the condition and challenges in maintaining accurate statistics and records among doctors, the actual number of cases is likely higher than reported.

During the follicular phase, concentrate on nutrient-rich foods that enhance energy, hormone balance, and overall health . This phase involves increasing estrogen levels, so it's important to choose foods that help balance these levels and prepare the body for ovulation.  Foods to include: Lean proteins: Chicken, turkey, fish, tofu, and beans provide essential building blocks for muscle health and hormone production.  Complex carbohydrates: Whole grains (quinoa, brown rice, oats), sweet potatoes, and legumes offer sustained energy and help regulate blood sugar.  Healthy fats: Avocados, nuts, seeds, and olive oil are vital for hormone production.  Cruciferous vegetables: Broccoli, cauliflower, cabbage, and kale can assist in balancing estrogen.  Fermented foods: Kombucha , sauerkraut , and kimchi support gut health and may aid in estrogen metabolism.  Leafy greens: Spinach, kale, and other leafy greens are rich in antioxidants and micronutrients like iron and folate . Berries: Strawberries, blueberries, and raspberries are packed with antioxidants and vitamins.  Eggs: Rich in protein, vitamins D, B2, and B12, eggs support cell growth.  Pumpkin seeds and flax seeds : Provide phytoestrogens and omega-3 fatty acids .  Foods to consider reducing: Refined carbohydrates: White bread, sugary snacks, and processed foods can cause blood sugar spikes and energy crashes.  Excessive sugar and processed foods: These can lead to inflammation and hormone imbalances.  In summary: Emphasize a balanced diet rich in lean proteins, complex carbohydrates, healthy fats, and nutrient-dense fruits and vegetables to support your body during the follicular phase.

During the luteal phase, prioritize foods high in protein, complex carbohydrates, and healthy fats, as well as those rich in magnesium, zinc, and vitamin B6 . These foods can assist in managing PMS symptoms, stabilizing blood sugar, and supporting progesterone production.  Foods to focus on: Lean protein: Chicken, fish, tofu, and beans aid in muscle repair and energy levels.   Complex carbohydrates: Legumes, brown rice, potatoes, oats, quinoa, and other whole grains help stabilize blood sugar.  Healthy fats: Omega-3 fatty acids from salmon, sardines, avocados, and flax seeds can enhance mood and reduce inflammation.  Magnesium-rich foods: Leafy greens, nuts, and seeds (especially pumpkin seeds) assist with bloating and muscle relaxation.  Zinc-rich foods: Oysters, red meat, beans, and nuts support progesterone production.  Vitamin B6-rich foods: Chicken, salmon, and starchy carbohydrates like sweet potatoes also support progesterone production.  Fiber-rich foods: Fruits like pears and prunes, root vegetables, leafy greens, and legumes aid digestion and manage cravings.  Vitamin C-rich foods: Bell peppers, kiwis, strawberries, oranges, and broccoli support overall health.  Foods to consider reducing or avoiding: Caffeine: It can disrupt your endocrine system and blood sugar levels. Processed soy: It can cause estrogen imbalance, particularly if you are sensitive to phytoestrogens.

Androgen insensitivity syndrome ( AIS ) is a condition characterized by the inability to respond to androgens, usually due to androgen receptor dysfunction. It occurs in 1 in 20,000 to 64,000 XY ( karyotypically male) births. This condition leads to a partial or complete inability of cells to respond to androgens . This lack of response can hinder or prevent the development of male genitals , as well as affect or inhibit the development of male secondary sexual characteristics during puberty . It does not significantly affect female genital or sexual development. Androgen insensitivity is clinically relevant only in genetic males, (i.e., individuals with a Y-chromosome , or more specifically, an SRY gene ). Clinical phenotypes in these individuals can range from a typical male habitus with mild spermatogenic issues or reduced secondary terminal hair , to a complete female habitus , despite having a Y-chromosome. AIS is classified into three categories based on the degree of genital masculinization : Mild androgen insensitivity syndrome (MAIS) is indicated when the external genitalia are typically male (a penis and a scrotum ). Partial androgen insensitivity syndrome (PAIS) is indicated when the external genitalia are partially, but not fully, masculinized . Complete androgen insensitivity syndrome (CAIS) is indicated when the external genitalia resemble those of a typical female (a vulva ) Androgen insensitivity syndrome is the most common cause of 46,XY undermasculinized genitalia . Management of AIS is currently focused on symptomatic management ; there is no available method to correct the defective androgen receptor proteins caused by AR gene mutations. Management areas include sex assignment , genitoplasty , gonadectomy to lower tumor risk, hormone replacement therapy , genetic counseling , and psychological counseling . Genetics The human androgen receptor (AR) is a protein encoded by a gene located on the proximal long arm of the X chromosome ( locus Xq11-Xq12). The protein coding region consists of about 2,757 nucleotides (919 codons ) spanning eight exons , labeled 1-8 or A-H. Introns vary in size from 0.7 to 26 kb . Like other nuclear receptors, the AR protein consists of several functional domains : the transactivation domain (also known as the transcription-regulation domain or the amino / NH2-terminal domain), the DNA-binding domain , the hinge region, and the steroid-binding domain (also referred to as the carboxyl-terminal ligand-binding domain). The transactivation domain is encoded by exon 1, constituting more than half of the AR protein. Exons 2 and 3 encode the DNA-binding domain, while the 5' part of exon 4 encodes the hinge region. The remaining portions of exons 4 through 8 encode the ligand binding domain. Trinucleotide Satellite Lengths and AR Transcriptional Activity The AR gene features two polymorphic trinucleotide microsatellites in exon 1. The first microsatellite, located nearest the 5' end, consists of 8 to 60 repetitions of the glutamine codon "CAG" and is referred to as the polyglutamine tract. The second microsatellite includes 4 to 31 repetitions of the glycine codon "GGC" and is known as the polyglycine tract. The average number of repetitions varies among ethnic groups, with Caucasians having an average of 21 CAG repeats and Blacks 18. In men, extreme lengths of the polyglutamine tract are linked to various diseases; fewer repetitions are associated with prostate cancer, hepatocellular carcinoma, and intellectual disability, while spinal and bulbar muscular atrophy (SBMA) is linked to 40 or more CAG repeats. Some research suggests an inverse relationship between the length of the polyglutamine tract and transcriptional activity in the AR protein, with longer tracts potentially linked to male infertility and undermasculinized genitalia. However, other studies have found no such correlation. A 2007 meta-analysis supports the correlation's existence, suggesting discrepancies can be resolved by considering sample size and study design. Some research also indicates that longer polyglycine tract lengths may be associated with genital masculinization defects in men, though other studies dispute this association. AR Mutations As of 2010, the AR mutation database has reported over 400 mutations, with the number continuing to rise. Inheritance is typically maternal and follows an X-linked recessive pattern; individuals with a 46,XY karyotype always express the mutant gene due to having only one X chromosome, while 46,XX carriers are minimally affected. Approximately 30% of AR mutations occur spontaneously and are not inherited. These de novo mutations result from a germ cell mutation or germ cell mosaicism in one of the parent's gonads, or a mutation in the fertilized egg itself. In one study, three out of eight de novo mutations occurred postzygotically, suggesting up to one-third result in somatic mosaicism. Not all AR gene mutations lead to androgen insensitivity; one specific mutation appears in 8 to 14% of genetic males but only affects a small number of individuals when other genetic factors are present. Other Causes Some individuals with CAIS or PAIS lack AR mutations despite having clinical, hormonal, and histological features that justify an AIS diagnosis; up to 5% of women with CAIS and 27 to 72% of individuals with PAIS do not have an AR mutation. In one patient, PAIS was attributed to a mutant steroidogenic factor-1 (SF-1) protein. In another case, CAIS resulted from a defect in transmitting a transactivating signal from the N-terminal region of the androgen receptor to the cell's basal transcription machinery. A coactivator protein interacting with the activation function 1 (AF-1) transactivation domain of the androgen receptor might have been deficient. The signal disruption could not be corrected by any known coactivators at the time, nor was the absent coactivator protein identified, leaving some experts skeptical that a mutant coactivator explains androgen resistance in CAIS or PAIS patients with a typical AR gene. XY karyotype Depending on the mutation, an individual with a 46,XY karyotype and AIS can exhibit a male (MAIS) or female (CAIS) phenotype, or may possess genitalia that are partially masculinized (PAIS). The gonads are testes regardless of phenotype due to the Y chromosome's influence. Therefore, a 46,XY female does not have ovaries and cannot contribute an egg for conception. In certain cases, 46,XY females develop a vestigial uterus and have been able to gestate children. Such instances are rare and have necessitated the use of an egg donor, hormone therapy, and IVF. Several case studies of fertile 46,XY males with AIS have been documented, although they are considered a minority. In some cases, infertile males with MAIS have managed to conceive children by increasing their sperm count through supplementary testosterone . A genetic male conceived by a man with AIS would not inherit his father's X chromosome , thus would neither inherit nor carry the gene for the syndrome. A genetic female conceived in this manner would receive her father's X chromosome and thus become a carrier . XX karyotype Genetic females (46,XX karyotype) possess two X chromosomes and thus have two AR genes. A mutation in one (but not both) results in a minimally affected, fertile female carrier. Some carriers have been observed to have slightly reduced body hair, delayed puberty, and/or tall stature, likely due to skewed X-inactivation. A female carrier will pass the affected AR gene to her children 50% of the time. If the affected child is a genetic female, she will also be a carrier. An affected 46,XY child will have AIS. A genetic female with mutations in both AR genes could theoretically arise from the union of a fertile man with AIS and a female carrier of the gene, or from a de novo mutation. However, given the rarity of fertile AIS men and the low incidence of AR mutation, the likelihood of this is small. The phenotype of such an individual remains speculative; as of 2010, no such documented case has been reported. Correlation of Genotype and Phenotype Individuals with partial AIS, as opposed to those with complete or mild forms, are born with ambiguous genitalia , making the decision to raise the child as male or female not straightforward. Unfortunately, precise knowledge of the AR mutation offers little insight into the phenotype ; the same AR mutation can lead to significant variation in masculinization levels among different individuals, even within the same family. The exact reasons for this variation are not fully understood, but potential factors include the lengths of polyglutamine and polyglycine tracts, sensitivity to and variations in the intrauterine endocrine environment, the impact of coregulatory proteins active in Sertoli cells , somatic mosaicism, expression of the 5RD2 gene in genital skin fibroblasts , and reduced AR transcription and translation from factors other than AR coding region mutations, an unidentified coactivator protein, enzyme deficiencies such as 21-hydroxylase deficiency , or other genetic variations like a mutant steroidogenic factor-1 protein. The extent of this variation is not uniform across all AR mutations and is more pronounced in some cases. Missense mutations that lead to a single amino acid change are known to produce the greatest phenotypic diversity. Pathophysiology Androgens and the Androgen Receptor The effects of androgens on the human body ( virilization , masculinization, anabolism , etc.) are not directly caused by androgens themselves but occur when androgens bind to androgen receptors; the androgen receptor mediates these effects in the human body. Similarly, the androgen receptor is generally inactive in the cell until it binds with androgens. The following steps illustrate how androgens and the androgen receptor collaborate to produce androgenic effects: Androgen enters the cell. Only specific organs in the body, like the gonads and the adrenal glands , produce the androgen testosterone . Testosterone is transformed into dihydrotestosterone , a chemically similar androgen, in cells that contain the enzyme 5-alpha reductase . Both androgens exert their effects by binding with the androgen receptor. Androgen binds with the androgen receptor. The androgen receptor is present throughout the tissues of the human body. Before binding with an androgen, the androgen receptor is attached to heat shock proteins . These heat shock proteins are released when androgen binds. Androgen binding prompts a stabilizing, conformational change in the androgen receptor. The two zinc fingers of the DNA-binding domain become exposed due to this new conformation. AR stability is believed to be supported by type II coregulators , which influence protein folding and androgen binding, or aid NH2/carboxyl-terminal interaction. The hormone-activated androgen receptor is phosphorylated . Receptor phosphorylation can occur prior to androgen binding, though the presence of androgen encourages hyperphosphorylation. The biological implications of receptor phosphorylation remain unknown. The hormone-activated androgen receptor translocates to the nucleus. Nucleocytoplasmic transport is partly facilitated by an amino acid sequence on the AR known as the nuclear localization signal . The AR's nuclear localization signal is mainly encoded in the hinge region of the AR gene. Homodimerization occurs. Dimerization is mediated by the second (nearest the 3' end) zinc finger . DNA binding to regulatory androgen response elements occurs. Target genes contain (or are flanked by) transcriptional enhancer nucleotide sequences that interact with the first zinc finger. These regions are referred to as androgen response elements. Coactivators are recruited by the AR. Type I coactivators (i.e., coregulators) are believed to affect AR transcriptional activity by facilitating DNA occupancy, chromatin remodeling , or the recruitment of general transcription factors associated with RNA polymerase II holocomplex. Target gene transcription follows. Thus, androgens bound to androgen receptors regulate the expression of target genes, thereby producing androgenic effects. In theory, some mutant androgen receptors can operate without androgens; in vitro research has shown that a mutant androgen receptor protein can trigger transcription without androgen if its steroid binding domain is removed. On the other hand, the steroid-binding domain might suppress the AR transactivation domain, possibly due to the AR's unliganded conformation. Androgens in fetal development Human embryos develop in a similar manner for the first six weeks, irrespective of genetic sex (46,XX or 46,XY karyotype); the only way to distinguish between 46,XX or 46,XY embryos during this period is to identify Barr bodies or a Y chromosome. The gonads start as tissue bulges known as the genital ridges at the back of the abdominal cavity , near the midline. By the fifth week, the genital ridges differentiate into an outer cortex and an inner medulla , and are termed indifferent gonads . By the sixth week, the indifferent gonads begin to differentiate based on genetic sex. If the karyotype is 46,XY, testes form due to the influence of the Y chromosome 's SRY gene. This process does not require androgen presence or a functional androgen receptor. Until about the seventh week of development, the embryo has indifferent sex accessory ducts , which include two pairs of ducts: the Müllerian ducts and the Wolffian ducts . Sertoli cells within the testes release anti-Müllerian hormone at this stage to inhibit the development of the Müllerian ducts, causing their degeneration. Without this anti-Müllerian hormone, the Müllerian ducts develop into the female internal genitalia ( uterus , cervix , fallopian tubes , and upper vaginal barrel ). Unlike the Müllerian ducts, the Wolffian ducts do not develop by default. In the presence of testosterone and functional androgen receptors, the Wolffian ducts transform into the epididymides , vasa deferentia , and seminal vesicles . If the testes do not secrete testosterone, or if the androgen receptors are not functional, the Wolffian ducts degenerate. Masculinization of the male external genitalia (the penis , penile urethra , and scrotum ), as well as the prostate , relies on the androgen dihydrotestosterone . Testosterone is converted into dihydrotestosterone by the 5-alpha reductase enzyme. If this enzyme is missing or deficient, dihydrotestosterone is not produced, and the external male genitalia do not develop properly. As is the case with the internal male genitalia , a functional androgen receptor is required for dihydrotestosterone to regulate the transcription of target genes involved in development. Pathogenesis of AIS Mutations in the androgen receptor gene can disrupt any stage of androgenization, from the synthesis of the androgen receptor protein to the transcriptional capability of the dimerized androgen-AR complex. AIS can occur if any of these steps are significantly impaired, as each is crucial for androgens to activate the AR and regulate gene expression . The specific steps affected by a mutation can often be predicted by identifying the mutation's location within the AR. This predictive ability is mainly retrospective, as the various functional domains of the AR gene have been understood through the analysis of specific mutations in different AR regions. For instance, mutations in the steroid binding domain have been shown to affect androgen binding affinity or retention , mutations in the hinge region affect nuclear translocation , mutations in the DNA-binding domain impact dimerization and DNA binding, and mutations in the transactivation domain affect target gene transcription regulation. However, even knowing the affected functional domain doesn't make predicting the phenotypical outcomes of a mutation straightforward. Some mutations can negatively impact multiple functional domains. For example, a mutation in one domain might adversely affect another by altering domain interactions. A single mutation can influence all downstream functional domains if it results in a premature stop codon or framing error , leading to a completely unusable (or unsynthesizable) androgen receptor protein. The steroid binding domain is especially susceptible to premature stop codons or framing errors, as it is located at the gene's end, making its information more prone to truncation or misinterpretation compared to other domains. More complex relationships have been observed due to mutated AR ; some mutations linked to male phenotypes have been associated with male breast cancer , prostate cancer , or in cases of spinal and bulbar muscular atrophy , diseases of the central nervous system . The male breast cancer seen in some PAIS cases is caused by a mutation in the AR's DNA-binding domain. This mutation is believed to disrupt AR's interaction with target genes, enabling it to act on additional targets, possibly in collaboration with the estrogen receptor protein, leading to cancerous growth . The pathogenesis of spinal and bulbar muscular atrophy (SBMA) shows that even the mutant AR protein itself can cause pathology . The trinucleotide repeat expansion of the polyglutamine tract in the AR gene associated with SBMA leads to the production of a misfolded AR protein that the cell cannot proteolyze and properly disperse. These misfolded AR proteins accumulate in the cell's cytoplasm and nucleus . Over 30 to 50 years, these aggregates build up and have a cytotoxic effect, eventually leading to the neurodegenerative symptoms associated with SBMA. Diagnosis The phenotypes associated with androgen insensitivity are not exclusive to AIS, so diagnosing AIS requires careful exclusion of other possibilities. Clinical signs suggestive of AIS include a short vagina or underdeveloped genitalia, partial or complete regression of Müllerian structures, bilateral nondysplastic testes, and impaired spermatogenesis and/or virilization. Laboratory results show a 46,XY karyotype and normal or elevated postpubertal testosterone, luteinizing hormone , and estradiol levels. The androgen binding activity of genital skin fibroblasts is generally reduced, though exceptions exist. The conversion of testosterone to dihydrotestosterone might be impaired. AIS is confirmed if androgen receptor gene sequencing identifies a mutation, although not all AIS cases (especially PAIS) will show an AR mutation (see Other Causes ). Each AIS type (complete, partial, and mild) has its own set of differential diagnoses to consider. There are reports of individuals with both AIS and certain conditions listed here, such as Klinefelter syndrome or Turner syndrome with mosaicism. The differential list varies depending on the suspected form of AIS: Chromosomal anomalies : Klinefelter syndrome (47,XXY karyotype) Turner syndrome (45,XO karyotype) Mixed gonadal dysgenesis (45,XO/46,XY karyotype) Tetragametic chimerism (46,XX/46,XY karyotype) Androgen biosynthetic dysfunction in 46,XY individuals : Luteinizing hormone (LH) receptor mutations Smith–Lemli–Opitz syndrome (associated with intellectual disability) Lipoid congenital adrenal hyperplasia 3β-hydroxysteroid dehydrogenase 2 deficiency 17α-hydroxylase deficiency 17,20 lyase deficiency 17β-hydroxysteroid dehydrogenase deficiency 5α-reductase deficiency Androgen excess in 46,XX individuals: 21-hydroxylase deficiency 3β-hydroxysteroid dehydrogenase 2 deficiency Cytochrome P450 oxidoreductase deficiency (disorder in mother causes 46,XX fetal virilization) 11β-hydroxylase deficiency Aromatase deficiency Glucocorticoid receptor mutations Maternal virilizing tumor (e.g. luteoma ) Increased androgen exposure in utero, not otherwise specified (e.g. androgenic drugs ) Developmental Mayer–Rokitansky–Küster–Hauser syndrome (46,XX karyotype) Swyer syndrome (46,XY karyotype) XX gonadal dysgenesis (46,XX karyotype) Leydig cell agenesis or hypoplasia , not otherwise specified (46,XY karyotype) Absent (vanishing) testes syndrome Ovotesticular DSD Testicular DSD (i.e. 46,XX sex reversal ) Teratogenic causes (e.g. estrogens , antiestrogens ) Other causes: Frasier syndrome (associated with progressive glomerulopathy) Denys–Drash syndrome (associated with nephropathy and Wilms tumor) WAGR syndrome (associated with Wilms tumor and aniridia) McKusick–Kaufman syndrome (associated with postaxial polydactyly) Robinow syndrome (associated with dwarfism) Aarskog–Scott syndrome (associated with facial anomalies) Hand-foot-genital syndrome (associated with limb malformations) Popliteal pterygium syndrome (associated with extensive webbing behind knees) Kallmann syndrome (often associated with anosmia) Hypospadias not otherwise specified Cryptorchidism not otherwise specified vaginal atresia not otherwise specified Management The management of AIS is currently restricted to symptomatic treatment ; there is no available method to rectify the defective androgen receptor proteins caused by AR gene mutations. Management areas include sex assignment , genitoplasty , gonadectomy concerning tumor risk, hormone replacement therapy , genetic couns eling , and psychological counseling .