Klinefelter's syndrome, characterised by a 47, XXY chromosomal pattern, has
largely been associated with physical abnormalities. Here, we report high
levels of schizophrenia-spectrum pathology in 32 men with this syndrome in
comparison with 26 healthy controls. This may have implications for
treatment of Klinefelter's syndrome and suggests that the X chromosome may
be involved in the aetiology of schizophrenia.