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What is Commonest genetic defect causing gonadal failure with primary amenorrhea and explain in detail?
Ans. d (Turner syndrome) (Ref. Shaw's Text book of Gynaecology 14th/ 97).Primary amenorrhea is defined as failure to menstruate by the age of 15in presence of normal secondary sexual development or withi 5 yrs after breast development, that occurs before age 10. The most common cause of primary amenorrhea is chromosomal abnormalities causing gonadal dysgenesis (45%), such as Turner's syndrome.Chromosomal syndromes1) Turner's syndrome# Commonest genetic defect causing gonadal failure with primary amenorrhea# 45X0# Streak gonads# Female genitalia with sexual infantilism# Short stature# Webbed neck# Primary amenorrhoea# Coarctation of the aorta and other variable physical features2) Klinefelter's syndrome# 47XXY# Dysgenesis of the seminiferous tubules# Male genitalia with small firm testicles# Tall stature# Gynecomastia# Learning/emotional difficulties3) True hermaphroditism# 46XX or 46XY or mosaic, ovaries, testes or ovotestes# Ambiguous or male genitalia with phallus# Bifid scrotum and hypospadias4) Mixed gonadal dysgenesis# Mosaic 45XO/46XY, streak gonads with ambiguous or female genitalia with mixed internal organ# Gonadectomy because of cancer risk and virilization5) Pure gonadal dysgenesis# 46 XY or 46XX, streak gonads with female genitalia.# 46XY is associated with clitoral hypertrophy, primary amenorrhoea, failure of sexual development and risk of gonadal cancer.# 46XX - no clitoral hypertrophy and no gonadal cancer risk6) 46XX males# Undescended testes with male/ambiguous genitalia# Short stature# Hypospadias.