What Causes Turner Syndrome?

Turner syndrome (TS) is the result of a chromosomal abnormality.

Usually, a person has 46 chromosomes in each cell, divided into 23 pairs, which includes two sex chromosomes. Half of the chromosomes are inherited from the father and the other half from the mother. A  chromosome contains genes, which determine an individual’s characteristics, such as eye color and height. Girls typically have two X chromosomes (or XX), but girls with Turner syndrome have only one X chromosome or are missing part of one X chromosome.

Turner syndrome is not caused by anything the parents did or did not do. The disorder is a random error in cell division that happens when a parent’s reproductive cells are being formed.

Girls born with the X condition in only some of their cells have mosaic Turner syndrome. Often, their signs and symptoms are milder than those of other girls with the non-mosaic condition.

What Are the Signs & Symptoms of Turner Syndrome?

Most girls with Turner syndrome are shorter than their peers, with an average final adult height of 4 feet 7 inches and may have other related physical features.

These can include:

• “webbing” of the skin of the neck (extra folds of skin extending from the tops of the shoulders to the sides of the neck)
• a low hairline at the back of the head
• low-set ears
• unusual eye features, including drooping of the eyelids
• altered bone development, especially the bones of the hands and elbows
• a lack of breast development at the expected age (usually by age 13)
• irregular periods or no periods (amenorrhea)
• a larger than usual number of moles on the skin

What Problems Can Happen?

Girls who have Turner syndrome don’t have typical ovarian development. They usually don’t develop
all the secondary sexual characteristics (the physical changes that usually happen in puberty) and are infertile (can’t become pregnant) as adults. However, advances in medical technology, including
hormonal therapy and in vitro fertilization, can help women with this condition.

Other health problems that may happen with TS include kidney and heart problems, high blood pressure, obesity, diabetes mellitus, thyroid problems, ear infections with decreased hearing, and altered bone development.

Girls with Turner syndrome usually have normal intelligence, but some may have learning problems, particularly in maths Many also struggle with tasks requiring spatial skills, such as map reading or visual organization. Hearing problems are more common in girls with TS.

They aren’t at increased risk for major psychological problems, but some girls do have problems with
body image or self-esteem, and some also might have ADHD.  Despite these physical differences and other problems, with the right medical care, early intervention, and ongoing support, a girl with Turner syndrome can lead a normal, healthy, and productive life.

How Is Turner Syndrome Diagnosed?

During a physical exam, a doctor may look for the physical features of Turner syndrome. These can vary widely — some girls with TS have many features or symptoms; others have only a few.

To diagnose Turner syndrome, doctors use a special blood test that looks at chromosomes, called a Karyotype test (chromosomal analysis). Results that indicate TS show only one X chromosome instead of two X chromosomes, with a total of 45 chromosomes instead of the usual 46. Some girls with Turner syndrome have two X chromosomes detected, but one is missing a piece.
Before birth, the condition may be found through karyotype or noninvasive prenatal testing (NIPT).
NIPT is done on the fluid surrounding the fetus, tissue from the placenta, or the blood from the mother. But these tests are not definitive for diagnosis of Turner syndrome. After birth, doctors can make a diagnosis with a karyotype or with a microarray test from the baby.

How Is Turner Syndrome Treated?

Because TS is a chromosomal disorder, there’s no cure for the condition. Although several treatments can help:

• Growth hormone, either alone or with other hormone treatment, may improve growth and will usually increase final adult height — often into the normal range if treatment is started early enough.
• Estrogen replacement therapy often begins when a girl is 12 or 13 years old to stimulate the development of secondary sexual characteristics (breast development and menstrual periods). This therapy will not reverse infertility, however.
• Cardiac surgery may be necessary to correct specific heart defects.
• Reproductive technologies can help women with Turner syndrome become pregnant.

Fertilized donor eggs are used to create embryos, which can be inserted into the uterus of a woman with TS. With the help of hormone treatment, the woman can carry a developing fetus to term.