PSYCHOSIS AND GENES WITH TRINUCLEOTIDE REPEAT POLYMORPHISM

Abnormal expansion of genes with trinucleotide repeat (TNR) polymorphi sm has been found in a number of neuropsychiatric disorders. These dis orders and the major psychoses, schizophrenia and bipolar affective di sorder, appear to share an interesting phenomenon: genetic anticipatio n. Because TNR expansion correlates with anticipation, these unstable DNA sites are considered important candidate loci for the major psycho ses. We investigated genes with TNR polymorphisms, including B1, B33, B37, and the N-cadherin gene, in unrelated Caucasian North American an d Italian schizophrenics (n = 53 to 74), and matched controls. Also, u nrelated Caucasian North American patients with bipolar I affective di sorder were screened for the B33 and N-cadherin genes (n = 49 and 63, respectively). No unusually long alleles that would suggest abnormal e xpansion of the TNR were observed for any of these genes. Also, no sta tistically significant results were found in tests for genetic associa tion between any of these genes and schizophrenia. For B37, a trend to ward a difference in allele counts between schizophrenics and controls was observed. However, no clear evidence for a role of these TNR-cont aining genes in schizophrenia or bipolar affective disorders was found .