In this prospective study, Han Chinese subjects who were candidates for carbamazepine therapy were screened for the HLA-B*1502 allele because of its association with the Stevens–Johnson syndrome and toxic epidermal necrolysis. The Stevens–Johnson syndrome (SJS) and its related disease, toxic epidermal necrolysis (TEN), are two of the most serious adverse reactions caused by drugs. SJS is characterized by high fever, malaise, and a rapidly developing, blistering exanthema of macular papules and target-like lesions, accompanied by mucosal involvement. This condition is associated with a rate of death of approximately 5%. TEN has a similar presentation, with even more extensive skin detachment and a death rate of 25 to 35%. 1 Carbamazepine, an anticonvulsant and specific analgesic agent for trigeminal neuralgia, is the most common cause of SJS–TEN in Southeast Asian countries. 2 We previously . . .