Question

Mental retardation in man associated with sex chromosomal abnormality is due to.

• A. Increase in X-complement
• B. Decrease in X-complement
• C. Large increase in Y-complement
• D. Moderate increase in Y-complement

Answer 1

Answer: (A)

Increase in X-complement

Sterile males with undeveloped. testes, mental retardation, etc. are due to the increase in their X-complement which takes place in a disorder called Klinefelter's syndrome. These are formed by the union of an XX egg and a normal y sperm or normal X egg and abnormal XY sperm. The individual thus has 47 chromosomes (44 + XXY).

So, the correct answer is 'Increase in X-complement'.