Question

Arrangement of sex chromosomes in Klinefelter's syndrome is

• A. $XX$
• B. $XY$
• C. $XXY$
• D. $XO$

Answer 1

Answer: (C)

$XXY$

Answer 2

Klinefelter's syndrome is formed by the union of an $XX$ egg and a normal $Y$ sperm or normal $X$ egg and abnormal $XY$ sperm. The individual has $47$ chromosomes $(44 + XXY)$. Such persons are sterile males with undeveloped testes, mental retardation, sparse body hair, and long limbs and with some female characteristics such as enlarged breasts. It is considered that the more the $X$ chromosomes, the greater is the mental defect. As the syndrome has two $X$ chromosomes, one barr body is seen in this case.