Which condition is characterized by testicular atrophy and gynecomastia?

Klinefelter's syndrome is characterized by the presence of an extra X chromosome in males, typically leading to a 47,XXY karyotype. This genetic condition results in a variety of clinical features, prominently including testicular atrophy and gynecomastia due to hormonal imbalances. The additional X chromosome affects the development of male reproductive organs and can lead to underdeveloped testes, significantly impacting testosterone production.

As a result of reduced testosterone levels, individuals may experience testicular atrophy, which is a decrease in testicular size. This hormonal imbalance can also lead to the development of breast tissue (gynecomastia), a condition not typically seen in normal male development.

Understanding Klinefelter's syndrome is crucial, as early identification and management of symptoms can improve quality of life, including addressing issues related to fertility, hormone replacement therapy, and psychological support. The other conditions listed—Down syndrome, Turner's syndrome, and Marfan syndrome—have distinct genetic origins and clinical features that do not align with the traits of testicular atrophy and gynecomastia.