Such transformation has already been seen with the mood-stabilizing agent carbamazepine, which underwent a US Food and Drug Administration boxed warning revision when an association between HLA-B*1502 and the risk of serious dermatologic adverse effects (Stevens-Johnson syndrome, toxic epidermal necrolysis) was identified in persons of Han Chinese descent (Ferrell and McLeod 2008). This evidence concerns the gene HLA-B and toxic epidermal necrolysis.