CD8A and toxic epidermal necrolysis: In support, Villani et al. observed clonal expansion in blister fluid/skin and blood in the majority of TEN patients, but not MDE patients, assayed by high-throughput TCR-Seq (14), and Pan et al. detected clonal expansion of drug-reactive cytotoxic CD8+ T cells in blister fluid and blood in carbamazepine-induced SJS/TEN by next-generation sequencing (45).