Klinefelter syndrome (KS or 47,XXY) is a genetic condition in which males are born with an extra X chromosome.

What Causes Klinefelter Syndrome?

Klinefelter syndrome (KS) happens at random. It is not anyone’s fault. KS is not passed down from parent to child.

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Rev. 1/2020. MassGeneral Hospital for Children and Massachusetts General Hospital do not endorse any of the brands listed on this handout. This handout is intended to provide health information so that you can be better informed. It is not a substitute for medical advice and should not be used to treatment of any medical conditions.