Significant linkage between bipolar affective disorder and chromosome 12q24.

Chromosome 12q23-q24.1 has been implied by a few linkage and association studies as a candidate region for affective disorder. The present study investigated for linkage between bipolar affective disorder and 16 microsatellite markers covering chromosome 12q22-q24 in two Danish families. Assuming homogeneity and a dominant mode of inheritance, a significant two-point lod score of 3.37 was found at D12S1639, when only bipolar patients were considered as affected. The lod score was supported by neighbouring markers. The empirical P-value for this lod score was 0.00002. Non-parametric analyses using SimIBD supported this finding, with P-values of 0.00003 and 0.005 at D12S1639. An overlapping segment of chromosome 12q24 was shared among all except one of the bipolar patients, with apparently different haplotypes in each family.