HLA-B*27 is significantly enriched in Nordic patients with psoriatic arthritis mutilans.

OBJECTIVES

The genetic contribution to psoriatic disease is substantial with a dominating influence of the HLA region. The profile of HLA class I genotypes likely contributes to shaping clinical phenotypes. Herein we aimed to explore such genotypes in cohorts of closely characterised subsets of psoriatic disease with special focus on psoriatic arthritis mutilans (PAM), a severe and rare form of psoriatic arthritis (PsA).

METHODS

Cohorts of patients with the diagnosis of psoriasis vulgaris with or without arthritis (n=1217), psoriasis without arthritis (n=534), psoriatic arthritis without mutilating disease (n=337) and psoriatic arthritis mutilans (n=63) were collected and genotyped for HLA class I and II genes, with standardised methodologies. Cases were compared with a healthy control population (n=2468). Case-only and case-control association tests were performed to address the hypothesis of genetic contribution to clinical phenotypes.

RESULTS

The presence of HLA-B27 was strikingly increased in PAM (45%) compared with PsA without mutilating disease (13%) and with healthy controls (13%). However, within the PAM population, HLA-B27 did not correlate with clinical markers such as number of mutilating joints, radiographic scoring, disease duration and age of disease onset.

CONCLUSIONS

HLA-B*27 emerges as an important genotype marker for PAM.