METHODS: 21 of 22 single nucleotide polymorphisms (SNPs) were successfully genotyped in independent cohorts of 1,398 PsA cases and 6,389 controls, and a group of 964 German PsV patients.
RESULTS: Association to a RUNX3 variant, rs4649038, was replicated in independent cases and controls and resulted in a combined p-value of 1.40E-08 in a Cochran-Mantel-Haenszel test and an OR of 1.24 (1.15-1.33). Further analyses based on linkage disequilibrium at RUNX3 refined the most significant association to a linkage disequilibrium (LD) block located in the first intron of one isoform. Weaker evidence for association was detected in German PsV patients (p-value 5.89E-02; OR 1.13 (1.00-1.28)), indicating a role in the skin manifestations of psoriasis.
CONCLUSION: Our analyses identified variants in RUNX3 as susceptibility factors for PsA. RUNX3 has already been implicated in susceptibility to ankylosing spondylitis, another spondylarthropathy, although its risk allele is independent from the PsA one. RUNX3 is involved in CD8 lymphocyte differentiation and therefore a good candidate for PsA and PsV as T-cell mediated diseases.