Klinefelter's syndrome is a syndrome in males characterized by small testes, hyalinization of seminiferous tubules, azoospermia, variable degrees of masculinization, and increased urinary excretion of gonadotropin. Patients tend to be tall, with long legs, and about half have gynecomastia. It is associated typically with an XXY chromosome complement, although variants include XXYY, XXXY, XXXXY, and several mosaic patterns. Called also seminiferous tubule dysgenesis and XXY s.
