What is a common clinical feature of Klinefelter syndrome in males?

Klinefelter syndrome is characterized by the presence of an extra X chromosome in males, typically resulting in a karyotype of 47,XXY. One of the notable clinical features of this condition is gynecomastia, which is the development of breast tissue. Unilateral breast enlargement can occur, although gynecomastia can also be bilateral. This feature is attributed to the imbalance of estrogen and testosterone levels that often accompanies this syndrome, leading to the proliferation of breast tissue.

The development of male secondary sexual characteristics is often affected in Klinefelter syndrome due to low testosterone levels, which can also correlate with testicular atrophy rather than increased testicular volume. Other common clinical features can include infertility and learning difficulties. In contrast, features like short stature or vaginal agenesis are not characteristic of Klinefelter syndrome; they are more suggestive of other genetic or developmental conditions.