A form of male HYPOGONADISM, characterized by the presence of an extra X CHROMOSOME, small TESTES, seminiferous tubule dysgenesis, elevated levels of GONADOTROPINS, low serum TESTOSTERONE, underdeveloped secondary sex characteristics, and male infertility (INFERTILITY, MALE). Patients tend to have long legs and a slim, tall stature. GYNECOMASTIA is present in many of the patients. The classic form has the karyotype 47,XXY. Several karyotype variants include 48,XXYY; 48,XXXY; 49,XXXXY, and mosaic patterns ( 46,XY/47,XXY; 47,XXY/48,XXXY, etc.).
Also Known As:
Klinefelter's Syndrome; Syndrome, Klinefelter's; 48,XXYY Syndrome; 49,XXXXY Syndrome; Klinefelter Syndrome, Variants; XXXY Males; XXY Syndrome; XXY Trisomy; Xxyy Syndrome; Klinefelter Syndromes; Klinefelter Syndromes, Variants; Klinefelters Syndrome; Syndrome, Klinefelter; Syndrome, Variants Klinefelter; Syndrome, XXY; Syndrome, Xxyy; Syndromes, Klinefelter; Syndromes, Variants Klinefelter; Syndromes, XXY; Syndromes, Xxyy; Trisomies, XXY; Trisomy, XXY; XXXY Male; XXY Syndromes; XXY Trisomies; Xxyy Syndromes