Further evidence for a bipolar risk gene on chromosome 12q24 suggested by investigation of haplotype sharing and allelic association in patients from the Faroe Islands.

A number of studies have strongly suggested a susceptibility locus for bipolar affective disorder on chromosome 12q24. The present study investigates for a shared chromosomal segment among distantly related patients with bipolar affective disorder from the Faroe Islands, using 17 microsatellite markers covering 24 cM in the previously suggested region on chromosome 12q24. D12S342 showed possible allelic association to bipolar affective disorder (P-value using CLUMP below 0.01). Increased sharing among cases of two-marker haplotypes were suggested at D12S1614--D12S342 (P-values using CLUMP below 0.01), and D12S2075--D12S1675 (P-values using CLUMP around 0.001). The region of most interest is around 6 cM and bounded by markers D12S1614 and D12S1675 as suggested by the interesting two-marker haplotypes. This area contains the minimum interesting region between D12S342 and D12S1658 suggested by the previously reported haplotypes in the two Danish families with bipolar affective disorder.