Definition: 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.).
index here karyotypes XXXY, XXXXY, XXYY, XXXYY, XX/XXY, XX/YY, XY/XXY, XXY/XXXY, XXY/XXYY, XY/XXY/XXXY if called KLINEFELTER SYNDROME by author but if not so named by author, index under SEX CHROMOSOME DISORDERS
Other names XXY Syndromes; XXXY Male; XX Male Syndromes; Syndromes, XXY; Syndromes, XX Male; Syndromes, Variants Klinefelter; Syndromes, Klinefelter; Syndrome, XXY; Syndrome, XX Male; Syndrome, Variants Klinefelter; Syndrome, Klinefelter's; Syndrome, Klinefelter; Klinefelters Syndrome; Klinefelter Syndromes, Variants; Klinefelter Syndromes; XXY Syndrome; XX Male Syndrome; Klinefelter's Syndrome; XXXY Males; Klinefelter Syndrome, Variants
