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Klinefelter's syndrome

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A congenital endocrine disturbance characterized chiefly by dull mentality and/or behavioural problems associated with hypogenitalism and hypogonadism. The affected children have small and firm testes, lack of sperm formation, but normal size penis, and gynecomastia (usually minimal). Long limbs and relatively slim and tall statures, but tendency towards obesity in some adults. Other features are immaturity, shyness, lack of judgement, assertive unrealistic activity. The majority of Klinefelter’s individuals have an extra female chromosome, resulting in an XXY pattern and a total of 47 chromosomes instead of 46. Other patterns of chromosomal aberration such as XXY, XXYY, and some mosaic patterns may result in the same syndrome. The most frequent type of intersexuality, one per 500-700 live male births.

The syndrome was reportedly first described in 1812, in 1895 by Richard Altmann (1852-1900), and worked over by Walther Berblinger (1882-1966) in 1934.

We thank Patrick Jucker-Kupper, Switzerland, for information submitted.


  • H. F. Klinefelter, Jr., E. C. Reifenstein, Jr., F. Albright:
    Syndrome characterized by gynaecomastia, aspermatogenesis without A-Leydigism and increased excretion of follicle-stimulating hormone.
    Journal of Clinical Endocrinology, Baltimore, 1942, 2: 615-627.

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