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Klinefelter Syndrome MeSH Descriptor Data 2026


MeSH Heading
Klinefelter Syndrome
Tree Number(s)
C12.050.351.875.253.795.500
C12.200.706.316.795.500
C12.800.316.795.500
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
Unique ID
D007713
RDF Unique Identifier
http://id.nlm.nih.gov/mesh/D007713
Annotation
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
Scope Note
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.).
Entry Term(s)
48,XXYY Syndrome
49,XXXXY Syndrome
Klinefelter Syndrome, Variants
Klinefelter's Syndrome
XXXY Males
XXY Syndrome
XXY Trisomy
Xxyy Syndrome
NLM Classification #
QS 677
Date Introduced
1966/01/01
Last Updated
2021/06/30
Klinefelter Syndrome Preferred
XXY Trisomy Narrower
Klinefelter Syndrome, Variants Narrower
48,XXYY Syndrome Narrower
49,XXXXY Syndrome Narrower
XXXY Males Narrower
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