Prevalence of the HLA-Cw6 genotype and zinc deficiency in psoriasis vulgaris patients in Indonesia

INTRODUCTION Psoriasis vulgaris is an immune-mediated inflammatory disease influenced by genetic and immunologic factors, including micronutrient deficiencies. The HLA-Cw6 gene and zinc level have been separately studied in psoriasis patients, yielding inconsistent findings. A descriptive study regarding HLA-Cw6 allele expression, zinc levels, and their direct correlation in Indonesia is lacking. METHODS This prospective case-control study involved 33 psoriasis patients and 33 age- and sex-matched control patients at the dermatology clinic affiliated with Hasanuddin University in South Sulawesi in 2021. Cases were classified into mild, moderate, and severe psoriasis according to Psoriasis Area and Severity Index (PASI) score. An EDTA tube was used to take a 5 ml blood sample, followed by analysis for PCR of the HLA-Cw6 allele and a colorimetric assay to measure zinc level. Statistical analysis was performed to determine the association between HLA-Cw6 and zinc level and psoriasis disease severity. RESULTS Among the 33 psoriatic patients enrolled in this study, three (9.1%) of the cases were classified as mild psoriasis, 10 (30.3%) were classified as moderate psoriasis, and 20 (60.6%) were classified as severe psoriasis. The HLA-Cw6 allele was detected in 93.9% of psoriasis cases and in 3% of control patients (p < 0.001). The HLA-Cw6 allele was detected consecutively in 66.7%, 90.0%, and 100% of mild, moderate, and severe psoriasis patients, respectively. Zinc levels were lower in psoriasis patients compared to controls (16.85 ± 3.55 vs. 13.74 ± 3.78 μmol/l). Severe psoriasis patients exhibited the lowest average zinc level (14.76 ± 1.40 μmol/l, 15.48 ± 4.20 μmol/l, and 12.72 ± 3.56 μmol/l in mild, moderate, and severe patients, respectively). The mean zinc level in HLA-Cw6-positive patients was 13.68 μmol/l, and 14.6 μmol/l in HLA-Cw6-negative patients (p = 0.495). CONCLUSIONS The study revealed the presence of HLA-Cw6 allele expression and decreased serum zinc levels in psoriasis patients compared to controls. Both factors demonstrated associations with psoriasis disease severity.