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BackgroundPrevious studies reveal that psoriatic arthritis (PsA) and ankylosing spondylitis (AS) share susceptibility genes, such as HLA-B27, demonstrating a degree of genetic overlap between these diseases. Recent studies have identified a number of novel AS and PsA genetic susceptibility loci, but data on these loci in Chinese PsA patients are limited.ObjectivesTo identify candidate genes that confer susceptibility to PsA in Chinese patients with PsA, psoriasis vulgaris (PsV), and healthy controls.Materials & MethodsSixteen susceptibility loci, reported in a genome-wide association study of AS, and nine susceptibility loci, reported in candidate gene studies of PsA, were examined. Single-nucleotide polymorphisms (SNPs) were genotyped in 503 patients with PsA, 496 patients with PsV, and 979 healthy controls using the SNPscanTM multiplex SNP genotyping platform. PLINK software and logistic regression analysis were used to estimate the statistical significance of associations.ResultsPPP2R3C (rs8006884) was shown to significantly associate with PsA+PsV (p = 1.92×10-3, OR = 1.28) and was suggested to associate with PsV (p = 0.03, OR = 1.19). A suggestive association was also observed between IL-23R (rs12141575) and PsA as well as with axial PsA based on subtype analysis, KIF3A (rs2897442) and PsV, and ERN1 (rs196941) or IFIH1 (rs984971) and axial PsA.ConclusionOur results suggest that PPP2R3C confers susceptibility to PsA and PsV, and that this gene may be related to the pathogenesis of psoriatic lesions and arthritis. Moreover, our results indicate a possible association between IL-23R, ERN1, or IFIH1 and subtypes of PsA, and between KIF3A and PsV.