Turner' Syndrome
Turner's Syndrome (also referred to as gonadal dysgenesis) is a relatively common genetic disorder of females, which affects many body systems. Approximately one in every 2,000-5,000 female babies has Turner's Syndrome. About 98-99% of pregnancies with Turner's Syndrome abort spontaneously, usually during the first trimester of pregnancy. Approximately 10% of fetuses from pregnancies that have spontaneously aborted have Turner's Syndrome.
Described by Dr. Henry Turner in 1938, this disorder in due to a deficiency in the amount of genetic material on the X-chromosome, one of the two sex chromosomes. Diagnosis of Turner's Syndrome is made with a chromosome analysis. Turner's Syndrome is not related to advanced maternal age and is a sporadic event, with the risk of recurrence not increased for subsequent pregnancies.
Turner's Syndrome is associated with short stature and failure to mature sexually. Other problems may include learning difficulties, skeletal abnormalities (e.g., webbed neck, low posterior hair line), lymphedema (swelling of a part of the body due to an obstruction or deficiency of the lymphatic drainage system), heart and kidney abnormalities, infertility, obesity, formation of keloids (thick scars), and thyroid gland dysfunction (hypothyroidism). The type and amount of missing genetic material influence which specific organ abnormalities will be present, as well as the person's potential for growth. Since the syndrome is not always accompanied by distinctive features, Turner's Syndrome is often not diagnosed during infancy, but may be suspected during childhood because of the short stature of a child. During teenage years, Turner's Syndrome may be discovered due to delayed puberty and menarche, while in adult woman, anovulation and infertility may indicate Turner's Syndrome.
Short stature is almost always present in females with Turner's Syndrome. The causes are intrauterine growth retardation, a gradual decline in growth rate during childhood, and the absence of a pubertal growth spurt. Females with Turner's syndrome have abnormal body proportions characterized by markedly shortened lower extremities. The ultimate height range is between 55 to 58 in, though familial height may play a role in determining the ultimate height that will be reached. Recent studies have indicated that much of the growth deficit in females with Turner's Syndrome can be restored by injections of human growth hormone.
Normal pubertal development and spontaneous menstrual periods do not occur in the majority of females with Turner's Syndrome. Though 10% of females with Turner's Syndrome will go through puberty spontaneously, most will require the use of female hormone therapy for development of secondary sexual characteristics and menstruation. The time of initiation of therapy varies with each female but usually begins when she expresses concern about the onset of puberty, usually around 15 years of age. Delaying the use of estrogen therapy is recommended to maximize the height the female will achieve. Various estrogenic and progestational agents and schedules have been used as hormone therapy. Although infertility cannot be altered, pregnancy may be possible through in vitro fertilization.
Renal abnormalities occur in 1/3 to 1/4 of females with Turner's syndrome. The most common abnormality is a horse shoe kidney. Cardiac abnormalities are also common, with the coarctation of the aorta being the most common. There is an increased incidence of thyroid dysfunction, diabetes mellitus, and carbohydrate intolerance. Prevalence of me ntal retardation appears to be no greater than in the general population, but Turner's Syndrome females may exhibit learning disabilities, especially with regard to spatial perception, visual-motor coordination, and mathematics. As a result, the nonverbal IQ in Turner's Syndrome tends to be lower than the verbal IQ. Females with Turner's Syndrome may also be socially immature for their age and may need support in developing independence and social relationships.
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