A multi-step genomic approach prioritized TBKBP1 gene as relevant for multiple sclerosis susceptibility

Background Over 200 genetic loci have been associated with multiple sclerosis (MS) explaining similar to 50% of its heritability, suggesting that additional mechanisms may account for the "missing heritability" phenomenon.Objective To analyze a large cohort of Italian individuals to identify markers associated with MS with potential functional impact in the disease.Methods We studied 2571 MS and 3234 healthy controls (HC) of continental Italian origin. Discovery phase included a genome wide association study (1727 MS, 2258 HC), with SNPs selected according to their association in the Italian cohort only or in a meta-analysis of signals with a cohort of European ancestry (4088 MS, 7144 HC). Top associated loci were then tested in two Italian cohorts through array-based genotyping (903 MS, 884 HC) and pool-based target sequencing (588 MS, 408 HC). Finally, functional prioritization through conditional eQTL and mQTL has been performed.Results Top associated signals overlap with already known MS loci on chromosomes 3 and 17. Three SNPs (rs4267364, rs8070463, rs67919208), all involved in the regulation of TBKBP1, were prioritized to be functionally relevant.Conclusions No evidence of novel signal of association with MS specific for the Italian continental population has been found; nevertheless, two MS loci seems to play a relevant role, raising the interest to further investigations for TBKBP1 gene.