Klinefelter syndrome has a prevalence of approximately 1 in 500 males. It results from the gain of an additional X chromosome in each cell, giving a 47,XXY male karyotype. The features are mild, children may present with small testes, small penis, hypospadias or cryptorchidism (undescended testes). They may have learning disabilities and difficulty with speech and language development. At puberty boys with Klinefleter syndrome can develop breast enlargement (gynecomastia), have reduced facial and body hair, tall stature and hypogonadism. Individuals with Klinefelter syndrome are invariably infertile and may present with azoospermia. Klinefelter syndrome cases arise as a sporadic event. However, 46,XX males have also been described with features of Klinefelter syndrome. In this case the syndrome results from the translocation of Y material (including the sex determining region, SRY) to the X chromosome during paternal meiosis. Klinefelter syndrome can also appear in a mosaic form, where normal cells are also present in the individual (a 47,XXY/46,XY karyotype). These individuals may exhibit a milder phenotype, which is dependent on the extent and tissue distribution of the normal cell line.
We accept postnatal blood samples from males with appropriate clinical features for a diagnosis of Klinefelter syndrome. Klinefelter syndrome may also be discovered as an incidental finding in prenatal cases or samples following pregnancy loss.
Price & reporting times
NHS referrals to this service are paid for where there is an existing specialist commissioning contract for genetic testing. In other cases please contact the lab for prices.
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Test validation & quality assurance - information for users
In some postnatal cases the quality of the chromosome preparations may be sufficient for the exclusion of Klinefelter syndrome only. This laboratory participates in the CEQAS quality assessment scheme for postnatal blood chromosome analysis.
5ml Lithium Heparin blood sample (1-2ml volume sufficient for younger/difficult to bleed patients)
Please see our referral guidelines for more information.