Physical and mental development of adolescent males with Klinefelter syndrome.

Of 25,000 Danish schoolboys, aged 15-16 years, 16 were found to have previously undiagnosed Klinefelter's syndrome. Comparison of these boys with normal controls indicated that on average these subjects had increased height, reduced weight, impaired hearing, slightly lowered intelligence, poor school performance, increased incidence of psychological consultation and lowered sexual activity compared with their peers.