Declining IQs of young males with the fragile X syndrome.

Retrospective, longitudinal data were obtained on 21 boys with the fragile X syndrome to assess whether their IQs declined during childhood. For the group as a whole, IQs dropped significantly; 13 boys showed a significant decline at retest. Our results are consistent with reports that young boys with the fragile X syndrome may be only mildly impaired, whereas adults with this syndrome are usually moderately or severely retarded. Parents of young boys with the fragile X syndrome should be cautioned that the IQ of their child may decline.