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.).

Descriptor ID	D007713
MeSH Number(s)	C12.706.316.795.500 C13.351.875.253.795.500 C16.131.260.830.835.500 C16.131.939.316.795.500 C16.320.180.830.835.500 C19.391.119.795.500 C19.391.482.629
Concept/Terms	Klinefelter Syndrome Klinefelter Syndrome Klinefelter Syndromes Syndrome, Klinefelter Syndromes, Klinefelter XXY Syndrome Syndrome, XXY Syndromes, XXY XXY Syndromes Klinefelter's Syndrome Klinefelters Syndrome Syndrome, Klinefelter's Klinefelter Syndrome, Variants Klinefelter Syndrome, Variants Klinefelter Syndromes, Variants Syndrome, Variants Klinefelter Syndromes, Variants Klinefelter 48,XXYY Syndrome 48,XXYY Syndrome Xxyy Syndrome Syndrome, Xxyy Syndromes, Xxyy Xxyy Syndromes XXY Trisomy XXY Trisomy Trisomies, XXY Trisomy, XXY XXY Trisomies 49,XXXXY Syndrome 49,XXXXY Syndrome XXXY Males XXXY Males XXXY Male

Below are MeSH descriptors whose meaning is more general than "Klinefelter Syndrome".

Below are MeSH descriptors whose meaning is related to "Klinefelter Syndrome".

Below are MeSH descriptors whose meaning is more specific than "Klinefelter Syndrome".