Insights into the pathogenesis of XXY phenotype from comparison of the clinical syndrome with an experimental XXY mouse model.

Klinefelter syndrome (47, XXY male) is the most common sex chromosome disorder in men. To study the underlying mechanisms of XXY phenotypes and design specific and novel therapeutic regimens for KS men, an experimental mouse model (41, XXY) was established. This manuscript compares the phenotypes of XXY men and mice and discusses the possible contributions of low androgen levels and extra X chromosome genes to the XXY phenotypes. The phenotypic similarities between XXY mouse and men suggest that the common genes that escape the X inactivation between XXY mouse and men may be responsible for the clinical manifestations in men with Klinefelter syndrome.