Question

XO-chromosomal abnormality in human beings causes

• A. Turner’s syndrome
• B. Down’s syndrome
• C. Klinefelter’s syndrome
• D. none of these

Answer 1

Answer: (A)

Turner’s syndrome is characterised by the monosomy of XO type. These are immature sterile females with webbed neck. Klinefelter’s syndrome is characterised by trisomy (XXY). These are male individuals, who are phenotypically fairly normal but have a fairly low sperm count and therefore sterile. Down’s syndrome is caused due to the presence of extra chromosome 21 (trisomy 21).