Which chromosomal condition is associated with gynecomastia?

• A. Klinefelter syndrome 47 XXY
• B. Turner syndrome 45 XO
• C. Down syndrome 21
• D. Triple X syndrome 47 XXX

Answer: (A)

Estrogenic stimulation of breast tissue outweighs androgen effects in this condition. In Klinefelter syndrome (47,XXY), the testes are often underfunctioning, producing less testosterone. Lower testosterone shifts the balance toward estrogen, and peripheral aromatization of androgens in adipose tissue can raise estrogen levels. This combination promotes breast tissue growth, so gynecomastia is a common finding in individuals with this chromosomal pattern.

The other listed conditions involve different gonadal function: Turner syndrome typically leads to estrogen deficiency in females; Down syndrome is not characteristically linked to gynecomastia; Triple X syndrome is a female chromosomal pattern, not associated with male gynecomastia.