Question

A 30 year old male complains of infertility. He appears tall and has gynaecomastia. Genitalia appear normal except for bilateral small testes. His chromosomal pattern is likely to be

• A. 45 XO
• B. 47 XXY
• C. 47 XYY
• D. 46 XY

Hint:

Tall male with gynaecomastia and small testes points to an extra X chromosome.

Answer 1

The Correct Option is B

Step 1: Understanding the Question.
A 30 year old male has infertility, tall stature, gynaecomastia (breast enlargement), and small testes on both sides, with otherwise normal genitalia. We need to find the chromosomal pattern that explains this picture.

Step 2: Key Concept.
This combination, tall build, small firm testes, gynaecomastia and infertility, is the classic picture of Klinefelter syndrome. Klinefelter syndrome is caused by an extra X chromosome in a male, giving the karyotype 47,XXY.

Step 3: Why this karyotype fits.
The extra X chromosome disrupts normal testicular development. The testes stay small and cannot make enough sperm or testosterone. Low testosterone with high estrogen activity leads to gynaecomastia, tall stature (from delayed epiphyseal closure), and infertility.

Step 4: Why the other options are wrong.
45,XO is Turner syndrome, seen in females with short stature, webbed neck and streak gonads, not in a male. 47,XYY is the "supermale" pattern, these men are usually tall but fertile, with normal genitalia and no gynaecomastia. 46,XY is a normal male karyotype and does not explain this clinical picture.

Step 5: Final Answer.
The chromosomal pattern is
\[ \boxed{47, XXY \text{ (Klinefelter syndrome)}} \]