Turner syndrome is a condition in which a woman is missing all or part of one X chromosome.
Normally, people have two sex chromosomes in each cell: Females have two X chromosomes, and males have an X and a Y.
But in Turner syndrome, one normal X chromosome is present, and the other X chromosome is nonfunctioning because it is missing, partially missing, or rearranged.
It’s also possible for a person with Turner syndrome to have what’s known as chromosomal mosaicism, or mosaic Turner syndrome, in which some cells have the normal number of X chromosomes and some do not.
Turner syndrome is considered a rare condition, estimated to occur in about 1 of every 2,000 to 2,500 live female births.
It’s named after Henry Turner, the American endocrinologist who first described the syndrome in 1938, and is also referred to as Ullrich-Turner syndrome, gonadal dysgenesis, or congenital ovarian hypoplasia.
Causes and Risk Factors of Turner Syndrome
While Turner syndrome is considered a genetic disorder, most cases are not inherited. (1)
A missing X chromosome results from a random event during the formation of the eggs or sperm in one of the parents of the affected person. This is called monosomy Turner syndrome.
Mosaic Turner syndrome results from a random event during cell division in early fetal development. As a result, some cells in the body of the affected person have two complete copies of the X chromosome, while other cells have only one copy.
In cases of Turner syndrome caused by a partial deletion of the X chromosome, cells have one complete and one altered copy of the chromosome. This error can occur in the father’s sperm or the mother’s egg, or as a result of cell division in early fetal development.
It's possible, but rare, for this form of the genetic defect to be passed from one generation to the next.
A small percentage of women with Turner syndrome have some cells with one copy of the X chromosome and others have one copy of the X chromosome and some Y chromosome material. Women with this form of the condition will develop biologically as female, but the presence of Y chromosome material increases their risk for developing a type of tumor called gonadoblastoma.
In general, though, the physical characteristics and health complications that arise for women with these chromosomal errors vary from person to person.
Risk Factors for Turner Syndrome
The loss or alteration of the X chromosome that causes Turner syndrome occurs randomly — sometimes as a result of problems with the father’s sperm or the mother’s egg and, for others, as a result of something that happens early in fetal development.
In general, it’s unlikely that parents of one child with Turner syndrome will have another child with the disorder, or that any family history of the condition increases a person’s risk for developing it.
Duration of Turner Syndrome
Turner syndrome affects different women in different ways. The condition is typically diagnosed before birth or shortly after birth, or during early childhood, but it may go undiagnosed in some women well into adulthood. (2)
However, once diagnosed, women with Turner syndrome must manage its symptoms and complications for the rest of their lives. Women with Turner syndrome can potentially develop a wide variety of health problems affecting many different organ systems — including the eyes, heart, kidneys, and digestive tract.
Complications of Turner Syndrome
Although most women with Turner syndrome can lead a normal life, with a close-to-average lifespan, the condition has been linked to an increased risk for a number of health complications, including: (1,7)
- Heart problems
- High blood pressure
- Hearing difficulties
- Vision problems
- Kidney problems
- Underactive thyroid (hypothyroidism)
- Celiac disease
- Inflammatory bowel disease
- Skeletal health issues
- Mental health problems and learning difficulties
- Infertility and pregnancy complications
Many babies born with Turner syndrome have heart defects that increase their risk for a number of heart diseases, including congestive heart failure.
Similarly, later in life, women with Turner syndrome have an increased risk of high blood pressure, which also increases their risk for developing diseases of the heart and blood vessels.
Hearing loss is also common with Turner syndrome, due in some cases to the gradual loss of nerve function in the ears. Women with the condition are also at increased risk for frequent middle ear infections, which can also cause hearing loss.
Hearing aids can help offset any hearing loss and improve performance in learning and social environments.
Girls and women with Turner syndrome are also more likely to have weakness in the muscles that control eye movements (strabismus), nearsightedness, and other vision problems.
Kidney deformities in girls and women with Turner syndrome may increase their risk for high blood pressure and urinary tract infections.
Women with Turner syndrome are more likely to develop hypothyroidism caused by the autoimmune disorder Hashimoto's thyroiditis, as well as diabetes, celiac disease (gluten intolerance), and inflammatory bowel disease (IBD).
Problems with the growth and development of bones in girls and women with Turner syndrome increase their risk for scoliosis (abnormal curvature of the spine) and kyphosis (rounding of the upper back), while older women with the condition are more likely to develop osteoporosis (or weak, brittle bones), which may cause them to experience more bone fractures.
Although most girls and women with Turner syndrome are of normal intelligence, they may be at increased risk for learning disabilities, as well as difficulties with math, memory, and attention. They may also have problems functioning well in social situations, and they may be at increased risk for attention deficit hyperactivity disorder (ADHD).
Finally, most women with Turner syndrome are infertile, although they may become pregnant following assisted reproductive technology involving in vitro fertilization with a donor egg. However, women with Turner syndrome are also at increased risk for high blood pressure and aortic dissection during pregnancy.
BIPOC Communities and Turner Syndrome
There are no known racial or ethnic differences that influence the frequency of Turner syndrome, but the prevalence of Turner syndrome in Black, Indigenous, and People of Color (BIPOC) communities has not been widely studied.
However, a survey of births in North Carolina over a five-year period found that the condition was most common in American Indian infants (5.1 in 10,000 live female births) and white infants (2.3 in 10,000 live female births), according to the March of Dimes. (9)
The same analysis found that 1.1 in 10,000 live female births among Black Americans in North Carolina between 2012 and 2016 had Turner syndrome.
Meanwhile, 1.8 in 10,000 live female births among Hispanic Americans in North Carolina between 2012 and 2016 had Turner syndrome.
Resources We Love
Turner Syndrome Society of the United States
The TSSUS educates and builds community among girls and women with Turner syndrome through webinars, Zoom meetings, and volunteer-led local Resource Groups. It also has a link to the Turner Syndrome Research Registry.
Turner Syndrome Clinic at Massachusetts General Hospital
MassGeneral offers basic information about Turner syndrome and its common complications, as well as advice on driving safely when you have Turner syndrome.
Turner Syndrome Foundation
The Turner Syndrome Foundation is an advocacy organization that supports research into Turner syndrome and offers support for those who have it via the Star Sisters program.
Turner Syndrome Global Alliance
The TSGA was founded by parents of girls with Turner syndrome to increase resources available to adults with Turner syndrome and to raise interest in and funds for research on the condition.
The Magic Foundation
The Magic Foundation provides support services to families of children with a variety of conditions that affect their growth, including Turner syndrome.
Additional reporting by Brian P. Dunleavy.
Editorial Sources and Fact-Checking
- Turner Syndrome: Symptoms and Causes. Mayo Clinic. November 18, 2017
- Turner Syndrome. National Organization for Rare Disorders (NORD).
- Oktay K, Bedoschi G, Berkowitz K, et al. Fertility Preservation in Females With Turner Syndrome: A Comprehensive Review and Practical Guidelines. Journal of Pediatric and Adolescent Gynecology. October 2016.
- Turner Syndrome: Diagnosis and Treatment. Mayo Clinic. November 18, 2017
- Turner Syndrome. Genetic and Rare Diseases Information Center. January 11, 2016.
- Life Expectancy. Centers for Disease Control and Prevention. March 17, 2017.
- Fuchs M, Jost C, Babovic-Vuksanovic D, et al. Long‐Term Outcomes in Patients With Turner Syndrome: A 68‐Year Follow‐Up. Journal of the American Heart Association. May 25, 2019.
- Turner Syndrome. Eunice Kennedy Shriver National Institute of Child Health and Human Development.
- Peristats: North Carolina. March of Dimes.
- Genetic Alliance (2009). Understanding Genetics: A New York, Mid-Atlantic Guide for Patients and Health Professionals (Appendix F: Chromosomal Abnormalities). Washington, DC.
- Chromosomal Conditions. March of Dimes. February 2013.