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

A number of studies have strongly suggested a susceptibility locus for bipo lar affective disorder on chromosome 12q24. The present study investigates for a shared chromosomal segment among distantly related patients with bipo lar affective disorder from the Faroe Islands, using 17 microsatellite mark ers 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-marke r haplotypes were suggested at D12S1614-D12S342 (P-values using CLUMP below 0.01), and D12S2075D12S1675 (P-values using CLUMP around 0.001). The regio n of most interest is around 6 cM and bounded by markers D12S1614 and D12S1 675 as suggested by the interesting two-marker haplotypes. This area contai ns the minimum interesting region between D12S342 and D12S1658 suggested by the previously reported haplotypes in the two Danish families with bipolar affective disorder.