Objective Linkage and association studies of bipolar affective disorder (BAD) point out chromosome 12q24 as a region of interest.
Methods To investigate this region further, we conducted an association study of 22 DNA markers within a 1.14 Mb region in a Danish sample of 166 patients with BAD and 311 control individuals. Two-hundred and four Danish patients with schizophrenia were also included in the study.
Results We observed highly significant allelic and genotypic association between BAD and two highly correlated markers. The risk allele of both markers considered separately conferred an odds ratio of 2 to an individual carrying one risk allele and an odds ratio of 4 for individuals carrying both risk alleles assuming an additive genetic model. These findings were supported by the haplotype analysis. In addition, we obtained a replication of four markers associated with BAD in an earlier UK study.
The most significantly associated marker was also analyzed in a Scottish case–control sample and was earlier associated with BAD in the UK cohort. The association of that particular marker was strongly associated with BAD in a meta-analysis of the Danish, Scottish and UK sample (P=0.0003).
The chromosome region confined by our most distant markers is gene-poor and harbours only a few predicted genes. This study implicates the Slynar locus. We confirmed one annotated Slynar transcript and identified a novel transcript in human brain cDNA.
Conclusion This study confirms 12q24.3 as a region of functional importance in the pathogenesis of BAD and highlights the importance of focused genotyping.
aCentre for Psychiatric Research, Aarhus University Hospital, Risskov
bBioinformatics Research Centre, Aarhus University, Aarhus
cInstitute of Human Genetics, Aarhus University, Aarhus
dH. Lundbeck A/S, Valby
ePsychiatric Centre Bispebjerg, University of Copenhagen, Copenhagen, Denmark
fDepartment of Psychiatry, University of Edinburgh, Royal Edinburgh Hospital, Edinburgh, UK
Correspondence to Henriette Nørmølle Buttenchøn, PhD, Centre for Psychiatric Research, Aarhus University Hospital, Skovagervej 2, Risskov 8240, Denmark
Tel: +45 77893575; fax: +45 77893599; e-mail: firstname.lastname@example.org
Henriette Nørmølle Buttenchøn and Leslie Foldager contributed equally to this study
Received 24 June 2009 Revised 2 December 2009 Accepted 7 December 2009
Supplementary data are available directly from the authors.