Interestingly, HLA-B*40:01 was found much more frequently in the allopurinol-induced MPE (n = 3/7; 42.9%) than others allopurinol-induced SJS-TEN (n = 2/13; 15.4%) and no HLA-B*40:01 was observed in allopurinol-induced DRESS cases. Here, HLA-B is linked to toxic epidermal necrolysis.