HLA-B and toxic epidermal necrolysis: The overall odds ratio of the association of the HLA-B*5801 gene and allopurinol-induced SJS/TEN in Thai was based on a meta-analysis study as 348 [8].The calculated incidence of allopurinol-induced SJS/TEN among subjects with HLA-B*5801 gene was based on highly internal valid sources, leading to the reliable estimate.