Genetics Northern California

Turner Syndrome

What is Turner syndrome?
How common is Turner syndrome?
What causes Turner syndrome?
How is Turner syndrome diagnosed?
Can Turner syndrome be diagnosed during pregnancy?
How is Turner syndrome treated?
Where can I get more information about Turner syndrome?

What is Turner syndrome?
Turner syndrome is a genetic condition in girls and women that causes short height and poor ovary development. The average adult with Turner syndrome is about 4 foot 8 inches. There may also be other physical differences, such as a thick neck, low hairline at the back of the head, low-set ears, droopingeyelids, and puffiness of the hands and feet at birth.

Learning in Turner syndrome

Girls with Turner syndrome usually have normal intelligence, but some may have learning problems.  

 

Medical concerns in Turner syndrome

Most girls with Turner syndrome have ovaries that do not work well. This means they may not start puberty at the typical time and may be infertile as adults. In addition, some girls with Turner syndrome are born with heart defects or kidney problems. There is also a higher chance of hearing loss.  

 

How common is Turner syndrome?

About 1 in every 2500 babies is born with Turner syndrome. Turner syndrome happens more often in early pregnancy, but many pregnancies with Turner syndrome miscarry during the first few months. Only 1% of Turner syndrome pregnancies continue to a full-term delivery. Turner syndrome can happen in any pregnancy to women of any age or ethnic background.


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What causes Turner syndrome?

Turner syndrome is caused by a missing sex chromosome. Humans usually have 46 chromosomes, which are paired into 23 pairs. We inherit one of each chromosome pair from our mother and the other from our father. One pair is called the sex chromosomes. The sex chromosomes include the genes for a person’s biological sex.  Usually, females have two X chromosomes, and males have one X and one Y chromosome. In Turner syndrome, there is a single X chromosome and the absence of a second sex chromosome (either an X or a Y). This is called 45,X or monosomy X. Some people with Turner syndrome have a mix of cells with the usual number of chromosomes (46) and some cells with a missing chromosome (45,X). This is called mosaic Turner syndrome. There are other variations as well.

 

Turner syndrome happens by chance and does not run in families. The age of the mother does not affect the chance to have a child with Turner syndrome. Nothing either parent did or didn’t do before pregnancy or during pregnancy is known to cause this condition.

 

How is Turner syndrome diagnosed?

A chromosome study done by a blood test or from a prenatal test can diagnose Turner syndrome. Testing can also show when a  person has mosaic Tuner syndrome or a different variation of Turner syndrome. The diagnosis may be suspected in a newborn with features of the condition, such as a heart defect and puffiness of the hands and feet. Turner syndrome may also be diagnosed in a girl who is small for her age or growing slowly. Some people with Turner syndrome are diagnosed as teens or young adults after a workup for late puberty or infertility.


Can Turner syndrome be diagnosed during pregnancy?

Turner syndrome can be diagnosed during pregnancy by either chorionic villus sampling (CVS) or amniocentesis. These tests look directly at the chromosomes from a developing baby.

 

Prenatal screening tests can look for Turner syndrome during pregnancy, but they do not give a final answer. Screening may be done by a blood test on the pregnant woman or by an ultrasound of the developing baby. If a screening test shows a higher chance for Turner syndrome, a diagnostic test is offered to find out for sure.


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How is Turner syndrome treated?
Treatments are available for many of the medical concerns in Turner syndrome. Medicine or surgery may be needed to treat heart defects. Hormone therapies can help increase height and start puberty. Fertility treatment may be done for women who want to become pregnant. Learning evaluations and early intervention can help with learning problems. There are also expert guidelines that outline the recommended care of girls and women with Turner syndrome. 

 

Where can I get more information about Turner syndrome?


Genetics Home Reference: Turner syndrome - General information about Turner syndrome provided by the National Library of Health. Also includes links to many related sites. 

Turner Syndrome Society - This site offers information and support for individuals with Turner syndrome and their families. 
 

Last reviewed: May 2020
Reviewed by: Kimberly Barr, MS, LCGC