Investigation of 36 non-HLA (human leucocyte antigen) psoriasis susceptibility loci in a psoriatic arthritis cohort

Psoriasis has been intensively studied recently and numerous risk-associated variants within 44 susceptibility loci have been discovered. Estimates suggest that the genetic contribution to PsA (psoriatic arthritis) may be higher than PsV (psoriasis vulgaris) yet most work has been done on the latter due to its greater population prevalence. To test whether variants in the PsV-associated loci are also related to PsA, we performed a candidate loci association study in Chinese population. Genotyping was performed by MassARRAY platform (Sequenom, San Diego, CA, USA). 50 single nucleotide polymorphisms (SNPs) with reported evidences for association with psoriasis were genotyped in 465 PsA cases and 421 healthy controls collected from Chinese population. Data handling, quality control and association analysis were performed using PLINK software (v. 1.07). SNPs in 5q33.3, 1p36 and 1q21.3 showed convincing evidence of association (rs7709212, P = 4.82 × 10 −5 , rs7536201, P = 3.89 × 10 −4 , rs1886734 P = 6.81 × 10 −4 , respectively). IL12B, RUNX3 and LCE were candidate genes in these regions. The combination of SNPs rs1886734 and rs7709212 was the best predictive model for PsA as compared to the control in test for gene–gene interaction. In conclusion, we assessed 36 non-HLA psoriasis susceptibility loci in PsA cohort, confirmed the association of three loci with PsA, these findings may help in developing possible genetic markers to predict PsA.