A. Down’s syndrome.
B. Patau syndrome.
C. Turner syndrome.
D. Klinefelter’s syndrome.
- Turner’s syndrome is the most common sex chromosomal disorder in phenotypic females.
- Turner’s syndrome results from complete or partial loss of one X chromosome (45, X) and is characterised by hypogonadism in phenotypic females
Features of Turner syndrome in children :‑
- The most severely affected patients generally present during infancy with edema (owing to lymph stasis) of the dorsum of the hand and foot and sometimes swelling of the nape f the neck.
- Swelling of the neck is related to markedly distended lymphatic channels, producing so called cystic hygroma.
- As these infants develop, the swelling subsides but often leave bilateral neck webbing and persistent looseness of skin on the back of the neck.
- Congenital heart disease is also common, particularly preductal coarctation of Aorta and bicuspid Aortic valve.
- C. VS abnormalities are most important cause of mortality in children with Turner ‘s syndrome.
- Features of Turner’s syndrome in Adolescents and Adult:-
- At puberty there is failure to develop normal secondary sex characteristics.
- The genitalia remains infantile, breast development is inadequate and there is little pubic hair. Nipples are widely spaced.
- Turner syndrome is the single most important cause of primary amenorrhoea accounting for approximately 1/3 of the cases.
- Short stature (height rarely exceeds 150 cm).
- The mental status of these patients is usually normal but subtle defects in nonverbal, visual spatial information processing have been noted (mental retardation is associated with the presence of extra chromosome not with loss of X chromosome).
- About 50% of the patients develop autoantibodies directed to the thyroid gland and upto one half of these patients develop hypothyroidism.
- Other features include low posterior hairline, webbing of neck, cubitus valgus, streak ovaries. o Glucose intolerance, obesity and insulin resistance are also seen.