Search

Background Pyoderma gangrenosum is a rare inflammatory disease of unknown etiology and unspecific histopathology. There are no clear-cut criteria for the diagnosis of this disease. The diagnosis is usually made based on clinical appereance, course of disease and possible, commonly coexisting disorders. In atypical cases the diagnosis is based on exclusion of other causes of similar appearing cutaneous ulcerations.

The identification of robust endotypes—disease subgroups of clinical relevance—is fundamental to stratified medicine. We hypothesized that HLA-C∗06:02 status, the major genetic determinant of psoriasis, defines a psoriasis endotype of clinical relevance. Using two United Kingdom–based cross-sectional datasets—an observational severe-psoriasis study (Biomarkers of Systemic Treatment Outcomes in Psoriasis; n = 3,767) and a large population-based bioresource (UK Biobank, including n = 5,519 individuals with psoriasis)—we compared demographic, environmental, and clinical variables of interest in HLA-C∗06:02–positive (one or two copies of the HLA-C∗06:02 allele) with those in HLA-C∗06:02‒negative (no copies) individuals of European ancestry. We used multivariable regression analyses to account for mediation effects established a priori. We confirm previous observations that HLA-C∗06:02–positive status is associated with earlier age of psoriasis onset and extend findings to reveal an association with disease expressivity in females (Biomarkers of Systemic Treatment Outcomes in Psoriasis: P = 2.7 × 10 –14, UK Biobank: P = 1.0 × 10 –8). We also show HLA-C∗06:02–negative status to be associated with characteristic clinical features (large plaque disease, OR for HLA-C∗06:02 = 0.73, P = 7.4 × 10 –4; nail involvement, OR = 0.70, P = 2.4 × 10 –6); higher central adiposity (Biomarkers of Systemic Treatment Outcomes in Psoriasis: waist circumference difference of 2.0 cm, P = 8.4 × 10 –4; UK Biobank: waist circumference difference of 1.4 cm, P = 1.5 × 10 –4), especially in women; and a higher prevalence of other cardiometabolic comorbidities. These findings extend the clinical phenotype delineated by HLA-C∗06:02 and highlight its potential as an important biomarker to consider in future multimarker stratified medicine approaches.