Frequency of HLA class I and II in an admixed Brazilian population with psoriasis

Psoriasis is a chronic, immune-mediated disease with a significant genetic component. The HLA-C*06:02 allele is one of the most strongly associated with the disease, particularly influencing early onset and severity. There are few current data on genetics in a Brazilian population with psoriasis.

This study aimed to investigate the genetic associations between human leucocyte antigen (HLA) alleles and psoriasis in a Brazilian admixed population.

We conducted HLA class I and II genotyping in 144 patients with psoriasis and compared the results with those of 720 controls. Additionally, we calculated the Psoriasis Area and Severity Index (PASI) and recorded whether the patient had current or previous systemic treatment for psoriasis and the age of disease onset.

HLA-B*13:02g, B*15:01g, B*37:01g, B*38:01g, B*57:01g, B*57:02g, B*13:02g, C*01:02g, C*06:02g, C*12:03g, C*18:01g, DRB1*01:02g, DRB1*04:08g and DPB1*04:01g alleles were associated with an increased risk of psoriasis (after the Bonferroni correction factor, only the HLA-C*06:02 remained significant). And HLA-DRB1*15:03g conferred protection against psoriasis after Bonferroni correction. Alleles significantly associated with PASI score < 10 were A*34:02g (p = 0.037) and B*50:01g (p = 0.037), while the allele related to PASI > 10 was DRB1*01:01g (p = 0.049). When comparing the age of disease onset, the following alleles were significantly associated with early onset psoriasis (before 30 years of age): B*44:03g (p = 0.010) and C*07:02g (p = 0.022).

The sample size was small compared with other international publications, and the subgroup of patients with mild disease was less represented; however, the combination of analytical approaches (univariate tests, PCA, and correction for multiple comparisons) reinforces the robustness of the work.

The present findings highlight the genetic complexity of psoriasis in a diverse population and suggest that it may not be directly linked to specific genetic factors. Further research is required to explore the environmental and genetic interactions that contribute to psoriasis pathogenesis.