Abstract: Objective：To determine the susceptibility loci of ankylosing spondylitis found by GWAS in patients with psoriatic arthritis (PsA). Methods: Nine susceptibility SNPs of ankylosing spondylitis were genotyped in 379 patients with PsA, 595 patients with psoriasis vulgaris (PsV) and 806 healthy controls by Sequenom MassARRAY. Results: ERAP1（rs27037，p=6.66×10-5，OR:1.43），chromosome 21q22.2 （rs2242944，P=1.07×10-3,OR: 0.73）and IL23R（rs1004819，P=4.58×10-3，OR：1.28）were significant association with susceptibility of PsA. ERAP1（rs27037， P=1.56×10-4，OR：1.35） associated with PsV. There was no heterogeneity of ERAP1（rs27037）between PsA and PsV groups and there was a heterogeneity of chromosome 21q22.2 (rs2242944) and IL23R (rs1004819) between them. IL23R（rs11209032）was found to be associated with axial PsA (P=1.57×10-3，OR: 1.52). Conclusion: ERAP1, 21q22.2 domain and IL23R are common susceptibility genes of both PsA and ankylosing spondylitis.

Key words: psoriatic arthritis, susceptibility gene;susceptibility loci, ankylosing spondylitis