HLA-B and Arthritis: The data showed that HLA-B*27:05:02 and HLA-B*39:01:01 were susceptibility alleles for PsA, but are not high-risk alleles for PsO in the absence of arthritis, and HLA-B*08:01 was associated with PsA susceptibility but appears protective for PsO, being significantly reduced in frequency in PsO (Table 3).