Clinical Phenotype and Disease Severity in Psoriasis with Genotype Correlation: A Cross-Sectional Study from Eastern India

Background: Psoriasis is a chronic immune-mediated inflammatory skin disease with a substantial genetic component. HLA-Cw6 and variants in the endoplasmic reticulum aminopeptidase 1 (ERAP1) gene have been implicated in psoriasis susceptibility and clinical heterogeneity. However, the relationship between these genetic markers and disease severity remains insufficiently characterized in Indian patients. Objective: To describe the demographic, clinical, and genotypic characteristics of patients with psoriasis and to assess associations of HLA-Cw6 status and ERAP1 rs26653 genotype with Psoriasis Area and Severity Index (PASI) scores and selected clinical features. Methods: This cross-sectional study included 100 patients with psoriasis. Demographic and clinical variables, including age, age at disease onset, disease duration, sex, clinical phenotype, scalp involvement, nail changes, and arthralgia, were recorded. Disease severity was assessed using the PASI. HLA-Cw6 status was determined, and ERAP1 rs26653 was genotyped using allele-specific polymerase chain reaction. Continuous and categorical variables were summarized descriptively. The Mann–Whitney U test was used for comparisons of PASI between two groups, while the Kruskal–Wallis test was used for comparisons involving three or more groups. Spearman’s rank correlation was used to assess associations between PASI and continuous variables, and Pearson’s chi-square test was used to evaluate associations between categorical variables. Statistical significance was set at p < 0.05. Results: The mean age of participants was 39.15 ± 15.93 years, and 70% were male. The mean PASI score was 12.13 ± 10.20. HLA-Cw6 was present in 52% of patients, while ERAP1 rs26653 genotypes were CC in 27%, GC in 41%, and GG in 32%. PASI did not differ significantly according to sex (p = 0.491), HLA-Cw6 status (p = 0.136), or ERAP1 rs26653 genotype (p = 0.933). No significant correlations were observed between PASI and age (ρ = 0.14, p = 0.154), age at onset (ρ = 0.07, p = 0.514), or disease duration (ρ = 0.14, p = 0.159). PASI differed significantly across clinical-phenotype categories (Kruskal–Wallis, p = 1.23 × 10⁻⁹). Conclusion: In this cohort of Indian patients with psoriasis, HLA-Cw6 status and ERAP1 rs26653 genotype were not significantly associated with PASI-defined disease severity. PASI varied significantly according to clinical phenotype. Larger studies with appropriate control groups and multivariable analyses are warranted to further characterize genotype–phenotype relationships in psoriasis. Keywords: Psoriasis; Psoriasis Area and Severity Index; HLA-C Antigens; Genetic Association Studies; ERAP1; Disease Severity