A chromosomal abnormality in which a male has one, or sometimes more, extra X chromosomes in his cells, giving a complement of XXY instead of XY. The risk of having a child with the condition increases with maternal age.
Symptoms and signs
Features of the syndrome differ in severity and may not be visible until the child reaches puberty, when gynaecomastia (breast enlargement) arises and the testes remain small. Affected males are generally infertile. They are often thin and tall with a feminine body shape and lack of body hair. Incidence of learning difficulties is higher in those people with Klinefelter’s syndrome than in the rest of the population.
There is no precise cure, however hormonal treatment can induce signs of puberty such as the growth of facial hair, and surgery can be used to put right the gynaecomastia.