About Turner Syndrome
Turner syndrome is variable, and each person will have unique health needs and characteristics.
Turner syndrome (TS) occurs in approximately one out of every 2,000- 4,000 live female births. It is a chromosomal condition describing girls and women with common features, physical traits, and medical conditions caused by the complete or partial absence of the second sex chromosome. TS was first described in the United States in 1938 by Dr. Henry Turner.
At the basic level, the missing genetic material prevents the female body from growing and maturing naturally. Turner syndrome is variable, and each person will have unique health needs and characteristics. Most girls and women have two complete X chromosomes (the sex chromosomes for females). Turner syndrome is caused by the absence of all or part of the second sex chromosome in some or all of the cells of the body. The most consistent features of TS are short stature and lack of ovarian development, however, there are other symptoms and characteristics that can appear in varying degrees, depending on each person's unique genetic makeup.
Symptoms and Characteristics of TS
Facial appearance, such as:
low-set and prominent ears
high, narrow roof of mouth
neck webbing ( short, thick neck)
lymphedema (puffy hands and feet)
turned up nails
short roots of teeth
chronic middle ear infections
distinctive heart, liver, and kidney abnormalities
autoimmune disorders, such as underactive thyroid and celiac disease
difficulty with nonverbal communication skills, spatial relationships, such as driving or riding a bike, and executive functions
The specific karyotype (genetic makeup of the chromosomes) does not always predict the appearance or medical symptoms of a person with TS.
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What is Turner Syndrome? Animated Explanation Video
What Causes Turner Syndrome?
Turner syndrome occurs when all or part of one of the X chromosomes is lost before or soon after the time of conception. To read a more detailed description of how this happens, please refer to the Guide for Families, pages 3-6.
There is nothing that either parent did before or at the start of the pregnancy that caused or increased the risk of TS for their daughter. The age of a parent, ethnicity, diet, or other factors are unrelated to the conception of a child with Turner syndrome.
Almost 50% of those with TS are missing the X chromosome in all of the cells that are tested (usually blood cells). This is written 45X and the medical term is monosomy X.
About 30% of those with TS have what is called mosaicism. This means that some cells have the complete number of chromosomes, written 46, XX, and the other cells are missing an X. It is believed that mosaicism is a result of the loss of an X chromosome after fertilization.
A Typical Human Karyotype
A Turner Syndrome Karyotype (45X)
Mosaicism in Turner Syndrome
An individual with mosaicism may have fewer health concerns, including less frequent or less severe heart problems and fewer problems with hand/foot swelling. A girl or woman who also has a fragment of the Y chromosome has an increased risk for developing a growth in the ovaries.
There are different types of mosaicism (a few are listed below):
45,X/46,XX - This can be harder to diagnose because they can, but not always, have fewer features related to TS, because fewer cells are missing an X.
45X/46,XY - This occurs in a small percentage of girls with TS. There are small fragments of Y chromosome in their cells, which can increase the risk of developing tumors, called gonadoblastomas, in their gonads (internal sex organs). These tumors are benign but can lead to cancerous tumors, so it is usually recommended that the ovaries be surgically removed.
It is important to remember that having Y chromosome material will not make a girl with TS have male features.
45,X/47XXX -This is a rare type of mosaicism in which there are 45 X cells and another cell type that has an extra X. These girls are typically taller.
About 20% of those with TS will have two X chromosomes, but one will be incomplete or have a different structure.
Ring chromosome - There are two X chromosomes, but one is shaped like a circle with the ends joined.
Isochromosome- The X chromosome has two long arms instead of a long and short arm.
Deletion - This occurs when the X chromosome is missing some of its genetic material.
Diagnosing Turner Syndrome
Turner syndrome can be diagnosed during fetal life, in infancy, during the late pre-teen period (8-12 years), or in late adolescence/early adulthood. A diagnosis after the age of 50 necessitates additional tests. The age of diagnosis has been decreasing with better awareness of TS in the medical community. Missed and delayed diagnosis of TS remains a major problem as there is no routine newborn screening for the condition.
Usually, there is something ‘different’ about a girl or woman that makes the parent or the doctor investigate the possibility of TS.
The Clinical Practice Guidelines for the Care of Girls and Women with Turner Syndrome recommends:
All females with suspected TS should have a genetic blood test, called a karyotype.
If mosaicism (a form of TS) is strongly suspected, but not confirmed with a standard karyotype, additional genetic testing should be done to confirm or rule out TS.
A blood karyotype is usually adequate, but skin cells or cheek (via swab) cells may be examined if there is an ongoing suspicion of TS or low-level mosaicism.
A final diagnosis is made by a blood test, called a karyotype, which looks at the complete set of chromosomes of an individual. A karyotype analysis determines if one of the X chromosome pairs is missing from the full chromosome set, or if there are any structural differences in the X chromosomes.
Before birth, a diagnosis of TS may be made by a maternal serum screening, by taking a sample of amniotic fluid or other fetal tissue, to look at the fetal karyotype or an ultrasound. Because ultrasound and maternal serum screening (blood tests) are not 100% reliable, genetic karyotype testing is essential after the baby is born so that the diagnosis of TS can be confirmed.
There are a range of health, developmental, social, and learning challenges that might affect girls and women with TS to different degrees, so it is important to diagnose TS as early as possible.
Early diagnosis helps doctors determine whether the person has health issues that need treatment or need to be followed.
NOTE: Males may have a 45,X/46,XY male mosaic karyotype, but this is not Turner syndrome. A TS diagnosis only applies to phenotypical females (those born with female sexual organs internally and externally). TSSUS professional advisors disagree with the practice of diagnosing males with TS and encourage physicians to contact TSSUS to consult with a TS genetic specialist for questions related to TS karyotypes.
Girls and women are diagnosed at various stages of life, from the prenatal stage to adulthood.
TS is a genetic condition associated with a range of health concerns.
Treating Turner Syndrome
TS is a chronic rare condition (clinically it is considered a disease, but of course, not infectious), associated with a range of health concerns.
The Clinical Practice Guidelines for the Care of Girls and Women with Turner Syndrome is a 70-page document describing health care recommendations for physicians and providers of care. The Patient and Family version of the Clinical Practice Guidelines is a 16-page document to support the partnership between those with TS, parents of girls with TS, and medical providers.
Turner syndrome is not directly treated by a doctor, but the individual health concerns that arise for each person with TS should be monitored and treated by an appropriate specialist. Treatment should be individualized and physicians, families, and patients should decide on treatment options together.
Major advances in treatment include growth hormone therapy to achieve greater height and estrogen replacement therapy to mimic natural estrogen. Other treatments specific to TS include advances in heart surgery, hearing evaluations, in-vitro fertilization, and social and psychological testing.
Connecting with others who share this unique bond and who have similar experiences and concerns is of great benefit. With the help of medical specialists and a good social support system, a woman with TS can expect to live a satisfying, healthy life.
Turner Syndrome Basics Video
Genetic Basics for Turner Syndrome Video