Genetic refinement and physical mapping of a chromosome 18q candidate region for bipolar disorder.

Recent genetic studies have implicated chromosome 18 in bipolar disorder (BP) with putative loci in the pericentromeric region and on 18q. We reported linkage to chromosome 18q21.33-q23 in a large family. In this study we typed additional markers in the family and were able to reduce the candidate region significantly. All affected family members are sharing alleles for markers spanning a genetic distance of maximal 8.9 cM. Haplotype analysis provided a marker order in agreement with published genetic and physical maps. Using yeast artificial chromosomes, we constructed a contig map that will help to identify positional candidate genes for bipolar disorder.