A recent study using a genome-wide association study in a Japanese population (including 14 allopurinol-related SJS/TEN patients and 991 ethnically matched controls) has discovered a set of SNPs in chromosome 6, particularly rs9263726 in the PSORS1C1 gene, rs2734583 in the BAT1 gene, and rs3094011 in the HCP5 gene that were closely linked with the HLA-B∗58 : 01 allele [13]. The gene discussed is HCP5; the disease is toxic epidermal necrolysis.