Genetic defect in Klinefelter's syndrome?

Ans. b (XXY) (Ref. H-17th/2340)KLINEFELTER'S SYNDROME# Most common chromosomal disorder associated with testicular dysfunction and male infertilty.# 1 in 1000 live-bom males.# Azoospermia is the rule in men with Klinefelter syndrome who have the 47, XXY karyotype.# Testicular histology :hyalinization of seminiferous tubules and absence of spermatogenesis. But number of Leydig cells appears to increase.# Testosterone is decreased and estradiol is increased.# Features:- Undervirilization and gynecomastia- Markedly reduced testicular volumes (1-2 mL)- Osteoporosis.# Increased risk of:- Breast cancer- NHL- Lung cancer.# Reduced risk of:- Prostate cancer.