Question

A person with 44A+XXY chromosome setup has gynecomastia and is barr body positive. They have symptoms of

• A. Turner's syndrome
• B. Klinefelter's syndrome
• C. Down's syndrome
• D. Edward's syndrome

Answer 1

Answer: (B)

Klinefelter's syndrome

Klinefelter’s Syndrome is aneuploid condition marked by the presence of one or more extra chromosomes in a male (44+XXY/ 44+XXXY/ 44+XXXXY). As we know that, to compensate the dosage of X-linked genes in human male and female, one X-chromosome in females is deactivated and is present as darkly stained body near nuclear envelope. The number of Barr bodies is always one less than the total number of X chromosomes. A human male with Klinefelter’s syndrome, 44+XXY/ 44+XXXY/ 44+XXXXY, can have 1, 2 or 3 Barr bodies, depending on the number of X-chromosome. The presence of extra copy of X-chromosome produces some feminine characters in otherwise male individuals. They are sterile feminised males with enlarged breasts (Gynecomastia). This makes option B correct.
Turner's Syndrome which is represented as 44 +XO; the individual are sterile females without Barr body and gynecomastia as they lack one X-chromosome. This makes option A incorrect.
Down's syndrome is called as trisomy 21 and is represented as 45 +XY or 45+XX.
Trisomy 18 causes Edward's syndrome that leads to severe physical birth defects in infants. Options C and D are incorrect as these are caused by defects in autosomes and do not exert any effect on sexual characters.
Therefore, the correct answer is option B.