Objective: A recent population-based study identified several HLA alleles as conferring a risk for psoriatic arthritis (PsA) among patients with psoriasis. The authors aimed to confirm these results using a family-based association study.
Methods: PsA probands, psoriasis probands and their first-degree family members were included. All participants were evaluated for the presence of psoriasis and inflammatory arthritis. HLA-B and -C genotyping was performed. The family-based association test was used to test for differences between PsA and psoriasis patients in transmission of candidate alleles from parents to offspring.
Results: A total of 178 PsA and 30 psoriasis probands and 561 first degree family members were analysed. The following HLA alleles were over-transmitted to PsA compared with psoriasis: HLA-C*12 (p=0.005), HLA-B*38 (p=0.04), HLA-B*39 (p=0.03), HLA-B*27 (p=0.002).
Conclusions: HLA-B*27, HLA-B*38, HLA-B*39 and HLA-C*12 alleles are potential PsA-specific genetic markers among patients with psoriasis.