OBJECTIVES: We identified a bipolar disorder (BPD) susceptibility region on chromosome 3q29 in a genome-wide linkage scan (Bailer et al. 2002 (Biol Psychiatry 52: 40), NPL-score 4.09) and follow-up linkage analysis (Schosser et al. 2004 (J Psychiatr Res 38(3): 357), NPL-scores >3 with five markers). These findings were supported by further fine-mapping of this region (Schosser et al. 2007 (Eur Neuropsychopharmacol 17(6-7): 501)), finding NPL-scores >3.9 with SNPs (single nucleotide polymorphisms) spanning a region of 3.46 Mbp in BPD families. Since genetic association studies are more powerful than linkage studies for detecting susceptibility genes of small effect size, we aimed to replicate these findings in an independent case-control sample collected in London (UK) and Vienna (Austria). METHODS: A total of 51 SNPs were genotyped using Sequenom MassARRAY(®) iPLEX Gold and tested for association in a sample of 526 cases suffering from DSM-IV and/or ICD-10 diagnosis of BPD and 691 controls. RESULTS: No genotypic and/or allelic association, as well as no haplotypic association, was found for any SNP after multiple testing correction. CONCLUSIONS: However, we cannot exclude the possibility that our sample might not have the power to detect rare variants associated with susceptibility to BPD. ; Alexandra Schosser, Monika Schloegelhofer, Karoline Fuchs, Mirjana Stojanovic, Nilufar Mossaheb, Jochen Kindler, Sarah Cohen-Woods, Georgina Hosang, Anne Farmer, Ian Craig, Peter McGuffin & Harald Aschauer