Original
1 in 500 seems to be the most used. Some studies say 1 in 1000. It only affects male as the Y chromosome is what makes one a male. Though I have read that some only have a very small piece of the Y present giving the newborn the appearance of female genitalia, though considered very rare. Research indicates only about 20% of males with KS are diagnosed though this should change with the availability of DNA tests.