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 have 
implications for treatment of Klinefelter's syndrome and suggests that the X 
chromosome may be involved in the aetiology of schizophrenia.