An allelic association study of two polymorphic markers in close proximity to a balanced translocation t(1:11) that co-segregates with mental illness.

We report a case control association study using polymorphic markers D1S1621 and D11S931 in unrelated individuals with schizophrenia, unipolar depression and a matched control group. The two polymorphic markers were identified during the positional cloning of the translocation breakpoint t(1:11)(q43:q14.3) that cosegregates with schizophrenia and affective disorders. These markers provided an opportunity to investigate linkage disequilibrium with a postulated schizophrenia susceptibility gene close to the translocation breakpoint in random populations of schizophrenia and unipolar depression individuals compared with a normal control population. No significant differences between allele frequencies for either of the markers in the affected populations were observed in comparison with the control group, which provides evidence against a nearby gene of major effect in the populations studied.