Physical mapping of a glutamate receptor gene in relation to a balanced translocation associated with schizophrenia in a large Scottish family.

The metabotropic glutamate receptor subtype 5a (mGluR5a) gene has been localised on the Gene Map of the Human Genome to chromosome 11q, approximately 1 cM from the genetic marker D11S931. D11S931 has been shown to lie close to a translocation breakpoint associated with schizophrenia and other psychiatric disorders in a large Scottish family. Because glutamate receptor genes are excellent candidates for psychiatric disorders, we have investigated the physical distance of this gene from the translocation breakpoint on chromosome 11. We have shown that the mGluR5a gene lies at least 850 kb from the breakpoint and, hence, cannot be directly disrupted in translocation carriers. However, a long range position effect of the translocation on this gene, or co-segregation of the translocation with a mutant allele of mGluR5a cannot be ruled out.