LAUSR

Abstract Background HLA‐B*58:01 is a well‐known risk factor for allopurinol‐induced severe cutaneous adverse reactions (SCARs). However, only a minority of HLA‐B*58:01 carriers suffer SCARs after taking allopurinol. The aim of this study was to investigate subsidiary genetic markers that could identify those at further increased risk of developing allopurinol‐induced drug reaction with eosinophilia and systemic symptoms (DRESS) in subjects with HLA‐B*58:01. Methods Subjects with B*58:01 were enrolled (21 allopurinol‐induced DRESS and 52 allopurinol‐tolerant control). HLA‐A, ‐B, ‐C and ‐DRB1 alleles were compared. Comparison of risk between HLAs and allopurinol‐induced SCAR in separate populations was performed to support the results. Kruskal‐Wallis test, Pearson's chi‐square test, Fisher's exact test and binary logistic regression were used to analyze the risk of SCAR development. Results Frequencies of A*24:02 (71.4 vs. 17.3%, p < 0.001, odds ratio [OR] = 12.0; 95% confidence interval [CI], 3.6–39.2) were significantly higher in B*58:01 (+) DRESS than B*58:01 (+) tolerant controls. In addition, DRB1*13:02 further increased the risk of DRESS. The phenotype frequency of A*24:02/DRB1*13:02 was significantly higher in the B*58:01 (+) DRESS group than in the B*58:01 (+) tolerant controls (52.4% vs. 5.8%, p < 0.001, OR, 66.0; 95% CI, 6.1–716.2). In 2782 allopurinol user cohort, the overall prevalence of DRESS was 0.22%, which increased to 1.62% and 2.86% in the presence of B*58:01 and B*58:01/A*24:02, respectively. Conclusion The additional secondary screening with A*24:02 and DRB1*13:02 alleles may identify those at further increased risk of allopurinol‐induced DRESS in B*58:01 carriers.