HLA-Cw6 and psoriasis

Abstract

Psoriasis is a multifactorial disease with a strong genetic background. HLA-Cw6 is one of the most strongly associated psoriasis susceptibility allele. It is repeatedly observed to affect disease course, phenotypic features, severity, comorbidities, and treatment outcomes. To the best of our knowledge, the roles of HLA-Cw6 in psoriasis have not yet been thoroughly reviewed. The worldwide frequency of HLA-Cw6 allele varies greatly, with HLA-Cw6 allele frequency being generally higher in Caucasians compared to Asians. The allele is associated with Type I early onset psoriasis. Stress, obesity, and streptococcal pharyngitis are commonly observed in HLA-Cw6 positive patients. Phenotypically, HLA-Cw6 is found to be associated with guttate psoriasis in some studies. In addition, patients carrying the allele are more likely to have arm, leg, trunk involvement, and Koebner's phenomenon. Psoriatic arthritis patients with HLA-Cw6 more often have early onset and tend to show cutaneous symptoms before musculoskeletal symptoms. HLA-Cw6 positive patients have been shown to be more responsive to methotrexate and ustekinumab in several studies. However, this difference in ustekinumab efficacy was only moderate in a post hoc analysis of phase III pivotal study. HLA-Cw6 positivity also tends to be less frequent in high-need patients who failed conventional therapy. Small studies have also investigated the role of HLA-Cw6 in remission of psoriasis during pregnancy, photosensitivity and atherosclerosis as comorbidity of psoriasis. Given the diverse nature of psoriasis pathogenesis, as well as the difference of HLA-Cw6 positivity in different ethnic groups, more studies are needed to confirm the role of HLA-Cw6 in psoriasis.

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