Unique motif shared by HLA‐B*59:01 and HLA‐B*55:02 is associated with methazolamide‐induced Stevens‐Johnson syndrome and toxic epidermal necrolysis in Han Chinese

Background Methazolamide (MTZ) has been occasionally linked to the lethal Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), which are associated with HLA-B*59:01. However, some MTZ-induced SJS/TEN (MTZ-SJS/TEN) cases are negative for HLA-B*59:01, implying that other genetic factors besides HLA-B*59:01 are contributing to MTZ-SJS/TEN. Objectives To comprehensively identify HLA and non-HLA genetic susceptibility to MTZ-SJS/TEN in Han Chinese. Methods Eighteen patients with MTZ-SJS/TEN, 806 subjects of the population control and 74 MTZ-tolerant individuals were enrolled in this study. Both exome-wide and HLA-based association studies were conducted. Molecular docking analysis was employed to simulate the interactions between MTZ and risk HLA proteins. Results We found a strong signal in the major histocompatibility complex region on chromosome 6 with 22 SNPs reaching exome-wide significance. Compared with MTZ-tolerant controls, a significant association of HLA-B*59:01 with MTZ-SJS/TEN was validated [odds ratio (OR) = 146.00, 95% confidence interval (CI): 16.12–1321.98; P = 6.19 × 10−10]. Moreover, 66.7% of MTZ-SJS/TEN patients negative for HLA-B*59:01 were carriers of HLA-B*55:02, whilst 2.7% of the tolerant individuals were observed with HLA-B*55:02 (OR = 71.00, 95% CI: 7.84–643.10; P = 1.43 × 10−4). Within HLA-B protein, the E45-L116 motif could completely explain the association of HLA-B*59:01 and HLA-B*55:02 with MTZ-SJS/TEN (OR = 119.33, 95% CI: 29.19–1227.96; P = 4.36 × 10−13). Molecular docking analysis indicated that MTZ binds more stably to the pocket of HLA-B*59:01 and HLA-B*55:02 than to that of non-risk alleles of HLA-B*40:01 and HLA-C*01:02. Conclusions This study confirmed the association of HLA-B*59:01 with MTZ-SJS/TEN and identified HLA-B*55:02 as a novel risk allele in Han Chinese with the largest sample size to date. Notably, the rs41562914(A)-rs12697944(A) haplotype, encoding E45-L116, is capable of serving as a powerful genetic predictor for MTZ-SJS/TEN with a sensitivity of 89% and specificity of 96%.