SCHIZOPHRENIA AND SEX-CHROMOSOME ANOMALIES

An apparent excess of sex chromosome aneuploidies (XXY, XXX, and possi bly XYY) has been reported in populations of patients with schizophren ia by a number of authors. These reports have received little attentio n because transmission of psychosis is regarded as autosomal and not s ex linked, and the detection of extra X chromosomes by Barr body estim ation alone is not a reliable procedure. In this article, we review st udies in which either complete karyotypes were determined for the whol e sample or in which the presence of a Barr body in an individual was checked by full cytogenetic analysis. We also add two studies (of the former type) of our own-on a Swedish hospital cohort and a United Stat es multiplex-schizophrenia family sample. These data, taken together, suggest that the sex chromosome aneuploidies, XXX and XXY, are increas ed in populations of patients with schizophrenia, whereas too few subj ects have been surveyed to determine whether an association also exist s with XYY. Nevertheless, we conclude that this is consistent with a g ene on the sex chromosomes having influence on the development of schi zophrenia. A sex chromosome locus is compatible with an autosomal patt ern of transmission if the gene is either pseudoautosomal (i.e., withi n the exchange region) or X-Y homologous (i.e., present in similar for m in the nonrecombining regions of both X and Y chromosomes).