Turner syndrome (TS), also known as Ullrich-Turner syndrome, is a genetic disorder affecting females due to a lack of one functional X chromosome between the normal pair. The chromosome in question may be completely absent or present only in part.
The genotype of TS is 45 XO instead of 46 XX, because one of the X chromosomes is missing. The symptoms of TS are quite varied, with some cases being so severe as to be diagnosed at birth, while a few females are diagnosed only when they fail to conceive in adult life.
Some of the most common clinical characteristics include:
Appearance at Birth
Baby girls with TS often have extra skin over the neck, because they have cystic malformations of the lymphatic tissue under the skin in this region. The skin here may appear webbed. The hairline is abnormally low, the ears are low-set, the hands and feet are puffy and the nails are soft.
Growth and Maturation Profile
Children with TS grow slowly and their adult height is shorter than usual. Puberty is typically absent, and the reason is that the ovaries fail to develop properly. This leads to lack of reproductive capability as well.
TS is associated with major anomalies of the heart and blood vessels as well as a high incidence of hypertension (40% in adult life). Some congenital heart problems include coarctation of the aorta and a bicuspid aortic valve. Mitral valve prolapse, ischemic heart disease and arteriosclerosis are other acquired problems.
In some women with TS, the kidneys are abnormal.
Lack of normal estrogen leads to weak bones, fracture risk and loss of height.
TS leads to a high risk of type 2 diabetes and hypothyroidism.
Most females with TS have normal intelligence. However, TS is associated with neurologic and psychological problems, including visuospatial incoordination (the child finds it difficult to locate objects in the space around her by sight) and difficulties with abstract thinking. Verbal skills are typically intact or superior compared to non-TS girls.
TS occurs in about 1 in 2500 female liveborn children, and no known environmental factor is to blame. It is not heritable.
Diagnosis and Management
The diagnosis may be made on the basis of the symptoms and physical findings and confirmed by a karyotype test, in which the chromosomes are examined under a microscope to detect if any are missing or abnormal. Treatment is symptomatic, such as the use of human growth hormone if detected in childhood, to increase the final adult height. Estrogen therapy in adolescence is necessary to mimic the secondary sexual development in normal puberty, such as breast development, but cannot bring about fertility without assisted reproduction. Combined estrogen and progesterone therapy may help to achieve menstruation, and the estrogen also helps protect against osteoporosis. Psychosocial therapy focused on helping the child cope with social and vocational demands, as well as to deal with self-esteem and cognitive issues, is helpful. Regular monitoring for other heart and endocrine problems, for instance, is essential.