it seems likely that it represents a false positive. In the gSEM GWAS we found the strongest statistical evidence to date linking variants in intron 1 of the OPRM1 gene to OA, extending previous candidate gene studies focused on this gene39,51,52. Gene-based analyses also identified two novel GWS genes for OA: PPP6C and FURIN. Examining the predicted differential expression of these genes in brain tissue and their colocalization with OA association signals suggest that the effect of the PPP6C locus on risk of OA is likely to be through effects on PPP6C expression, while the signal for OPRM1 is more complex; there is limited evidence that expression differences explain the association of FURIN with OA.
