XX male syndrome

XX male syndrome (also called de la Chapelle syndrome) is a rare sex chromosomal disorder in men. Usually it is caused by unequal crossing over between X and Y chromosomes during meiosis. Symptoms include small testes, gynecomastia and sterility.

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Men typically have one X chromosome and one Y chromosome in each diploid cell of their bodies. Women typically have two X chromosomes. XX males have two X chromosomes, but otherwise appear to be male.

See also

• X chromosome, for other diseases related to the X chromosome.

References

• de la Chapelle A (1972). "Analytic review: nature and origin of males with XX sex chromosomes". Am J Hum Genet 24 (1): 71-105. PMID 4622299.