Turner Syndrome

Turner syndrome (TS) is a chromosomal condition that causes developmental problems in females, occurring when one of the two X chromosomes normally found in women is either missing or incomplete. The condition was first identified by Dr. Henry Turner in the late 1930s, but was not defined as a chromosomal deficiency until almost 30 years later.

Today, TS occurs in 1 out of every 2,500 births worldwide, making it one of the most common chromosomal abnormalities. There are approximately 60,000 girls and women living with this condition in the United States, and approximately 800 new cases diagnosed every year. In most cases, fetuses with TS do not survive to term, making up about 10 percent of the total number of miscarriages and stillbirths in the U.S.

Causes and characteristics

Humans normally have 46 chromosomes, two of which determine a person's gender. A woman's sex chromosomes help her become fertile and develop the female sexual characteristics, so when one of the two X chromosomes is partially or completely absent, various developmental problems can occur. With TS, the seriousness of these problems depends on how many cells are affected by the missing or incomplete X chromosome. The more cells affected, the more pronounced the effects.

One of the most common characteristics of women and girls with TS is a short stature. If the syndrome is diagnosed while a girl is still growing, hormone treatment can help her grow taller, but those who go untreated will only reach an average height of about 4 feet 8 inches.

In addition to growth problems, another common characteristic of TS is a lack of proper ovarian development. Because the ovaries are responsible for releasing the hormones that cause breast growth and menstruation, most girls with TS will not go through all the changes that come with puberty. As a result, almost all women with this condition will be infertile or unable to conceive on their own.

Other physical features of TS may include a webbed neck, drooping eyelids, arms that slightly turn out at the elbow, puffiness or swelling of the hands and feet, low-set ears, a low hairline and a broad chest.

There are also a number of health problems that occur more often in girls with TS than in healthy girls. These include cardiovascular problems, high blood pressure, kidney and thyroid problems, diabetes, cataracts, hearing difficulties and skeletal disorders, such as scoliosis or dislocated hips.

Not everyone with TS experiences the same symptoms. Some may exhibit several of the physical effects, while others experience only a few. With early treatment, most women and girls with TS can lead normal, healthy lives.

TS is not associated with any environmental or other factors generally associated with genetic problems, and despite many efforts, the cause of the condition has not yet been found. At this point, it has been determined a random condition that can affect anyone.

Diagnosis

TS is generally diagnosed in utero, at birth or around the time a girl would normally be expected to go through puberty. During pregnancy, a fetus with TS can be diagnosed by an amniocentesis, or identified by abnormal ultrasound findings, such as a heart defect or kidney abnormality. If a baby girl shows physical signs of TS when she is born, she will be given a karyotype, a blood test which analyzes her chromosomal makeup by counting and identifying any abnormally shaped chromosomes or chromosomes that have missing pieces. In some cases, there are no recognizable signs that a girl has TS until she hasn't gone through puberty when she would normally be expected to.

Treatment

Because it a chromosomal condition that forms during fertilization, there is no cure for TS. There are a number of treatments, however, that can help correct some of the problems and minimize the symptoms of the condition.

• Growth hormone - If started early enough, growth hormone treatment can improve growth and affect a girl's final adult height. Covered by most insurance plans and approved by the Food and Drug Administration for treatment of TS, growth hormone can help many girls reach a final height in the average range of a woman without TS.



• Estrogen replacement - Since TS was first described by Dr. Turner in the late 1930s, estrogen replacement therapy has been used to promote development of secondary sexual characteristics, such as breasts, pubic hair and eventually menstrual periods. Estrogen replacement therapy is also beneficial in maintaining good tissue and bone integrity, and is typically started when a girl is about 12 or 13 years old.



• Advanced reproductive technologies - Modern fertility techniques, such as in vitro fertilization, can make it possible for women with TS to become pregnant. A donor egg can be used to create an embryo which can be carried to term and delivered by a woman with TS as long as she has proper medical support.

Living with TS

TS can affect people in many ways, but the condition does not define a person's entire life. Women and girls with the condition may have a different style of learning, in which verbal skills come more easily while math or special learning is more difficult, but the majority of those with TS are able to attend regular classes and lead successful lives. For more information, visit the Turner Syndrome Society's Web site.