Turner syndrome (TS) is a genetic condition that affects females. This chromosomal disorder limits development, resulting in short stature, delayed puberty, reduced fertility and several other medical concerns. TS affects approximately one out of every 2,500 live female births.
Turner Syndrome Causes and Risk Factors
People usually have 46 chromosomes, in 23 pairs of two. These include two sex chromosomes: Females typically have two X chromosomes, and males typically have one X chromosome and one Y chromosome. Changes in the structure, number or grouping of chromosomes result in chromosomal disorders.
Turner syndrome is a type of chromosomal disorder that affects the X chromosome. Females with Turner syndrome only have one normal X chromosome. The second X chromosome may be structurally abnormal, missing pieces or absent entirely. This condition is not inherited—a random mutation causes the chromosomal changes.
Turner Syndrome Symptoms
Turner syndrome can cause a variety of distinct physical features and medical concerns. Each child is different, so your child may not experience all symptoms. The type of TS may affect the number and severity of symptoms.
Physical characteristics
The most common physical sign of Turner syndrome is short stature. Common facial features include:
- Drooping eyelids
- High, narrow roof of the mouth
- Low hairline
- Low-set ears
- Small jaw
Other common physical characteristics of Turner syndrome include:
- Abnormal bone development
- Above average number of moles
- Lymphedema (puffy hands or feet)
- Webbed neck (extra folds of skin)
Medical conditions
Turner syndrome can affect many different organs and body systems. Some conditions may be present at birth, while others may develop later. Once your child is diagnosed with TS, doctors can watch your child for these known related conditions and treat them if any develop.
Conditions associated with TS include:
- Congenital heart defects
- Kidney and liver abnormalities
- Frequent middle ear infections and hearing problems
- Autoimmune disorders, such as thyroid disease, celiac disease and diabetes
- Learning difficulties
Turner Syndrome Types
Turner syndrome has several types based on the X chromosomes present in a person’s cells. The two main types are:
- Monosomy X (45X): People with this type of Turner syndrome lack part or all of a second X chromosome in all their body’s cells. Monosomy X tends to cause more symptoms that are often more severe.
- Mosaic Turner syndrome (mosaicism): Mosaic Turner syndrome occurs when some cells in the body have two normal X chromosomes, while other cells are missing part or all of the second X chromosome.
Turner Syndrome Diagnosis
Doctors may diagnose Turner syndrome in females:
- Before birth
- In infancy
- During childhood
- During adolescence/early adulthood
Early diagnosis allows doctors to monitor and treat children with TS for potentially serious medical complications that may arise. The Clinical Practice Guidelines for TS recommends testing for Turner syndrome if your daughter has:
- A left-side heart defect
- Characteristic physical features
- Delayed puberty or menstruation
- Hydrops (accumulation of fluid in a fetus)
- Infertility
- Unexplained slow growth or short stature
Diagnostic tests
Doctors may use the following tests to diagnose your child:
- Physical exam: A doctor looks for physical signs of TS.
- Blood karyotype test: This blood test looks at the number and structure of your child’s complete set of chromosomes. Karyotyping is the standard method for diagnosing monosomy X and some types of mosaicism.
- Skin or cheek cell karyotyping: Sometimes the blood karyotype test does not provide a definitive diagnosis for mosaic TS. In these cases, doctors may take skin cells or a cheek swab to get more tissue samples for karyotyping.
- Magnetic resonance imaging (MRI): Doctors may use MRI scans to look for common liver, kidney and heart defects that are associated with TS. Learn more about cardiac MRI.
- Maternal serum testing: Diagnosing TS during pregnancy is increasingly common. Doctors use an amniocentesis to sample amniotic fluid or chronic villus sampling (CVS) to get a fetal tissue sample. Then they perform karyotyping on the sample to look for TS. If your child receives a tentative TS diagnosis before birth, doctors will perform a blood karyotype test when your child is born to confirm it.
- Fetal ultrasound: A fetal ultrasound may show some of the physical characteristics or conditions associated with TS, but ultrasound alone is not enough for a diagnosis.
Heart Defects Associated With Turner Syndrome
Approximately half of females with Turner syndrome, a genetic condition affecting the X chromosomes, are born with heart problems. Those who aren’t born with heart conditions remain at higher risk for developing heart disease throughout their lives.
Congenital (from birth) heart defects related to Turner syndrome typically affect the left side of the heart and aorta. The aorta is the largest artery—it carries oxygenated blood from the heart to the rest of the body.
Common heart conditions in children with Turner syndrome include:
- Bicuspid aortic valve: The valve controlling blood flow from the heart into the aorta only has two flaps, instead of the usual three. This is the most common heart defect among people with Turner syndrome.
- Coarctation (narrowing) of the aorta: The artery carrying blood from the heart to the body is too narrow. This narrowing causes the heart to pump harder.
- Aortic dilatation (widening): When the aorta is wider than usual, it is more likely to rupture (aortic dissection). Children with Turner syndrome need regular cardiac imaging to watch for this serious condition.
- Aortic stenosis: The valve from the heart into the aorta is too narrow, which restricts blood flow into the aorta. Aortic stenosis can also increase pressure in the left side of the heart.
- Anomalous pulmonary venous return (APVR): The veins carrying oxygen-rich blood from the lungs connect to the wrong part of the heart. Usually, oxygenated blood enters the left side of the heart, which can pump it out to the rest of the body. In children with APVR, the oxygenated blood goes to the right side of the heart instead. It mixes with blood that hasn’t yet received oxygen from the lungs, making it harder for the organs to get enough oxygen.
- Other left heart anomalies: Less often, children with Turner syndrome may experience hypoplastic left heart syndrome or other types of underdeveloped left heart.
Monitoring Turner Syndrome Heart Defects
If your child has Turner syndrome, it is important to go to a cardiologist to look for any potential heart problems. The doctor will perform an echocardiogram to check your child’s heart structure and function. If the echocardiogram doesn’t fully show your child’s aorta, the doctor may request a cardiac MRI.
All children with Turner syndrome need ongoing cardiac monitoring:
- Children with current or past heart problems need annual blood pressure monitoring, echocardiograms and electrocardiograms, along with cardiac MRIs every three to five years.
- Children with aortic dilatation need follow-up appointments every six months.
- Children with no history of heart problems need annual blood pressure monitoring, along with an echocardiogram and/or MRI every five years and before any pregnancies.
Treating Turner Syndrome Heart Defects
Some heart defects may not require immediate treatment. When necessary, treatments include lifestyle changes, medication and surgery:
- Lifestyle changes: Cardiac problems are an ongoing concern for people with Turner syndrome. Addressing any treatable risk factors, such as high cholesterol or obesity, can help reduce the risk for developing heart complications. Getting regular exercise and eating a healthy diet are important parts of a healthy lifestyle.
- Cholesterol medication: When lifestyle changes are not enough, doctors may prescribe medication to lower cholesterol.
- Blood pressure medication: High blood pressure is another common heart condition among people with Turner syndrome. High blood pressure can also increase the risk of complications from heart defects like aortic dilatation. It is important to monitor and treat any blood pressure issues. Doctors may prescribe beta blockers to lower blood pressure.
- Heart surgery: Many heart problems associated with Turner syndrome eventually require heart surgery. At CHLA, our surgeons have expertise in procedures correcting heart defects associated with TS. These include aortic root replacements, valve repairs and surgical treatment of hypoplastic left heart syndrome.