Turner Syndrome, X0

Turner syndrome (TS) is a congenital condition (present from birth) that exclusively affects females. It occurs when one of the two X chromosomes is either partially or completely missing.

Turner syndrome results in a range of features and symptoms, impacting each individual differently. However, short stature and reduced ovary function (primary ovarian insufficiency) are the two most prevalent characteristics.

Turner syndrome affects 1 in 2,000 to 1 in 2,500 female infants. It is the most common condition related to sex chromosomes in newborn girls.

Symptoms and Causes

Humans generally have 23 pairs of chromosomes (46 in total). These chromosomes are divided into 22 numbered pairs (autosomes) and one pair of sex chromosomes. Each biological parent contributes one chromosome to form a pair.

The 23rd pair typically consists of one X and one Y chromosome in males and two X chromosomes in females. Turner syndrome occurs when one of a baby’s two X chromosomes is missing or incomplete. Researchers have yet to determine why this happens.

Types of Turner syndrome

Turner syndrome (TS) can vary based on how one of the X chromosomes is affected:

Monosomy X: In this type, each cell contains only one X chromosome instead of two. Approximately 45% of individuals with TS have monosomy X. This chromosomal anomaly occurs randomly during the formation of reproductive cells (eggs or sperm) in the biological parent of the affected person. If one of these atypical reproductive cells contributes to the genetic composition of a fetus during conception, the baby will be born with a single X chromosome in each cell.
Mosaic Turner syndrome: This type accounts for about 30% of TS cases. Some of your child’s cells have two X chromosomes, while others have only one. It occurs randomly during cell division early in pregnancy.
Inherited Turner syndrome: In rare instances, babies may inherit TS, meaning their biological parent was born with it and passed it on. This type typically results from a missing part of the X chromosome.

What are the symptoms of Turner syndrome?

Turner syndrome manifests in various ways. It can lead to multiple characteristics or features, as well as certain health conditions, which can differ in severity. Depending on the type of TS, signs of the syndrome may be noticeable:

Before birth.
Shortly after birth.
In early childhood.
In early adolescence.
In adulthood.

Since TS affects everyone differently, you should consult your healthcare provider about what symptoms and features to expect or watch for based on your or your child’s unique genetic profile.

Common features of Turner syndrome

The primary feature of Turner syndrome is short stature. Nearly all individuals with TS:

Grow more slowly than their peers during childhood and adolescence. Short stature typically becomes noticeable by age 5.
Experience delayed puberty and lack of growth spurts, resulting in an average adult height of 4 feet, 8 inches. (If your child is diagnosed early, growth hormone therapy can increase their height by up to 5 inches, leading to an average adult height of 5’1”.)

Another common feature is differences in sexual development. Most individuals with TS:

Typically do not undergo puberty unless they receive hormone therapy in late childhood and early adolescence.
May not experience breast development without hormone therapy.
May not have menstrual periods (amenorrhea).
Have smaller-than-expected ovaries that may only function for a few years or not at all (primary ovarian insufficiency or POI).
Have low levels of sex hormones (such as estrogen).
Experience infertility.

In addition to short stature, individuals with Turner syndrome often exhibit certain physical characteristics, which may include:

Unique ear features, such as low-set ears, elongated ears, cup-shaped ears, and thick ear lobes.
A low hairline at the back of the neck.
A small and receding lower jaw, potentially affecting tooth development and alignment.
A short, broad neck or a webbed neck with extra skin folds.
A broad chest.
Arms that slightly angle outwards at the elbows (cubitus valgus).
Absence of a knuckle in a specific finger or toe, making it shorter than the others.
Flat feet (pes planus).
Narrow fingernails and toenails.
Numerous small colored spots (pigmented nevi) on the skin.

Health conditions linked to Turner syndrome

Individuals with Turner syndrome have an increased risk of certain health conditions, though not everyone with TS will experience them.

Cardiovascular conditions

Those with Turner syndrome may encounter heart and blood vessel issues, some of which can be severe. Up to 50% of individuals with TS are born with a congenital heart condition affecting the heart's structure. Cardiovascular issues may include:

Bicuspid aortic valve.
Coarctation of the aorta.
Elongation of the aortic arch.
High blood pressure (hypertension).

Bone Conditions

Bone conditions are frequently observed in TS and can include:

Higher risk of osteoporosis and bone fractures (breaks), particularly if estrogen therapy hasn’t been administered.
Scoliosis, affecting about 10% of individuals with TS.

Autoimmune Conditions

TS elevates the risk of certain autoimmune disorders, such as:

Celiac disease.
Hashimoto’s thyroid disease (a form of hypothyroidism).
Inflammatory bowel disease (IBD).

Hearing and Vision Issues

Hearing and ear issues commonly found in individuals with TS include:

Frequent middle ear infections (otitis media), which can lead to mastoiditis and/or cholesteatoma formation. These often occur between ages 1 and 6.
Sensorineural hearing loss, developing in over 50% of adults with TS.

The most prevalent vision and eye issues include:

Refractive errors (nearsightedness and farsightedness).
Crossed eyes (strabismus).
Lazy eye (amblyopia).
Drooping eyelids (ptosis).

Other less common concerns include red-green color blindness and blue sclera.

Other Associated Conditions

Individuals with Turner syndrome might also experience:

Kidney conditions: Structural issues in the kidney-urinary system occur in approximately 30% to 40% of individuals with TS. This may involve horseshoe kidneys or the absence (agenesis) of a kidney. Urine flow problems can lead to urinary tract infections (UTIs).
Metabolic syndrome: Individuals with TS have a heightened risk for metabolic syndrome, a collection of conditions that elevate the risk of developing cardiovascular disease, Type 2 diabetes, and stroke.
Lymphedema: This condition can result in swollen, puffy hands and feet.
Learning disabilities: Those with Turner syndrome typically have normal intelligence levels but face a higher risk of learning disabilities. This often involves difficulties with visual-motor and visual-spatial skills, making it challenging to perceive how objects relate to each other in space. For instance, driving might be difficult.
Mental health challenges: Living with Turner syndrome may lead to self-esteem issues and/or chronic stress, potentially causing anxiety and/or depression.

Diagnosis and Tests

How is Turner syndrome diagnosed?

Healthcare providers can diagnose Turner syndrome at any point in a child's development after birth. Occasionally, the condition is detected before birth using the following tests:

Noninvasive prenatal testing (NIPT): This is a screening blood test for the pregnant woman. It looks for signs indicating an increased likelihood of a chromosomal issue with the fetus.
Ultrasound during pregnancy: An ultrasound may reveal that the fetus has certain physical features of TS, such as heart problems or fluid around the neck. Additional tests like amniocentesis or chorionic villus sampling may be requested to confirm the diagnosis.
Amniocentesis and chorionic villus sampling: These tests examine the amniotic fluid or tissue from the placenta. Providers conduct a genetic test with karyotype analysis on the fluid or tissue, which can confirm if the fetus has Turner syndrome.

In other cases, children are diagnosed shortly after birth or during early childhood due to their symptoms. However, some individuals are not diagnosed with Turner syndrome until adulthood. These individuals may experience puberty and menstruation but often have primary ovarian insufficiency (early menopause).

After birth, a genetic test with karyotype analysis is used to confirm a Turner syndrome diagnosis. This test requires a blood sample.

Management and Treatment

How is Turner syndrome treated?

Turner syndrome cannot be cured, but various medications and therapies can help manage its symptoms.

In addition to addressing related medical issues (such as heart conditions), treatment for Turner syndrome often emphasizes hormones. Treatment options may include:

Human growth hormone therapy: Administering human growth hormone injections supports vertical growth. When initiated early, these injections can increase the child’s final height by several inches.
Estrogen therapy: Individuals with TS often have low estrogen levels, a hormone crucial for sexual development. Estrogen aids in breast development and menstruation. It also enhances brain development, heart and liver function, and bone health.
Cyclic progestins: These medications help induce regular menstrual cycles. Healthcare providers usually start them around ages 11 or 12.

Who should be on my child’s care team for Turner syndrome?

Treatment for Turner syndrome is tailored to each child’s unique symptoms and development. A coordinated care team offers the most comprehensive and effective care, considering the overall situation and creating a plan tailored to your child.

Typically, children with Turner syndrome primarily consult their pediatricians. They also undergo assessment and monitoring by pediatric endocrinologists, who are specialists in hormones and can advise on addressing hormone deficiencies.

Other pediatric specialists might include:

Cardiologists.
Ophthalmologists.
Otolaryngologists (ENTs).
Nephrologists.
Psychologists.

Parents can assist the healthcare team by maintaining growth charts and observing other symptoms. Families are also advised to seek genetic counseling.

Prevention

Is it possible to prevent Turner syndrome?

Turner syndrome cannot be prevented. It occurs randomly during conception. Biological parents cannot prevent it, and it is not their fault.

Outlook / Prognosis

What should I expect if my child has Turner syndrome?

It's crucial to understand that each individual with Turner syndrome is affected differently. Predicting its impact on your child is impossible. The best preparation is consulting healthcare providers who specialize in Turner syndrome.

What is the life expectancy for someone with Turner syndrome?

Individuals with Turner syndrome may have a slightly reduced life expectancy. However, by diagnosing and treating related health conditions, those with Turner syndrome can anticipate a typical lifespan.

Living With

How can I care for my child with Turner syndrome?

Early diagnosis is essential. Monitor your child's growth and developmental milestones. If you notice your child isn't growing as expected or observe unusual physical symptoms, discuss your concerns with their pediatrician.

Certain treatments, like hormone therapy, are most effective when started early. It's also vital to address other medical issues, such as cardiac concerns. Regular monitoring and checkups are necessary to track your child's health and any issues.

Healthcare providers suggest that children with Turner syndrome:

Undergo screening for learning disabilities: This should be done as early as 1 or 2 years old. Collaborating with your child's teachers can help tackle issues before learning disabilities become more severe.
Consult a mental health professional: A therapist, such as a child psychologist, can assist with social challenges, low self-esteem, anxiety, and depression. Cognitive-behavioral therapy (CBT), a form of psychotherapy (talk therapy), can aid your child in managing these difficulties.

What questions should I ask my doctor?

If your child is diagnosed with Turner syndrome, inquire with your healthcare provider about:

What treatment options are available?
What are the potential risks and benefits of growth hormone injections and other hormone therapies?
When should hormone treatments be initiated?
What other medical conditions might my child be susceptible to?
Which specialists should be included in their care team?
What types of learning disabilities might occur?
What resources are available to help meet my child’s specific needs?