TDT analysis of D22S278 & bipolar disorder in a Palestinian Arab population

A number of linkage studies suggest a schizophrenia susceptibility locus on chromosome 22 particularly with microsatellite marker D22S278 (22q12). In addition to some evidence for linkage to schizophrenia in this region, linkage to bipolar disorder using this marker has also been reported. In the current report we have tested a group of 60 bipolar I triads and an expanded group of 79 bipolar I & bipolar II triads recruited from a Palestinian Arab population for linkage with the D22S278 marker. Significant linkage was observed using the allele-wise Extended Transmission Disequilibrium Test for multiallelic markers (ETDT) for both bipolar I (p=0.031) and the expanded group of bipolar I and bipolar II (p=0.041). These weakly positive results are at least consistent with the hypothesis that this region of chromosome 22 might harbor a susceptibility locus for both major psychoses and should be considered for more intensive study.