Klinefelter’s syndrome

A chromosomal abnormality in which a male has 1, or occasionally more, extra X chromosomes in his cells, giving a complement of XXY instead of XY. The risk of a baby having the condition increases with maternal age. Features of the syndrome vary in severity and may not become apparent until puberty, when gynaecomastia (breast enlargement) occurs and the testes remain small. Affected males are usually infertile (see infertility). They tend to be tall and thin with a female body shape and absence of body hair. Incidence of learning difficulties is higher in people with Klinefelter’s syndrome than in the general population. There is no cure for the disorder, but hormonal treatment can induce secondary sexual characteristics, and mastectomy may be used to treat gynaecomastia.


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