Phenytoin-induced Stevens-Johnson syndrome with negative HLA-B*1502 allele in mainland China: two cases.

Antiepileptic drugs-induced Stevens-Johnson syndrome (SJS) is a life-threatening severe cutaneous adverse reaction. Recent studies in Thailand and Taiwan showed a significant association between phenytoin (PHT)-induced SJS and human leucocyte antigen HLA-B*1502 allele. Although the US FDA had issued an alert to clinicians, insufficient information is available to recommend testing for HLA-B*1502 in Asian patients in line for PHT treatment. Therefore, extended studies are necessary to further evaluate the potential association between PHT-induced SJS and HLA-B*1502 allele in various populations. To date, no similar data exist in mainland China. Here, we describe two Chinese Han cases of PHT-induced SJS with negative HLA-B*1502 allele, in which HLA high-resolution genotyping showed two heterozygous HLA-B*4601/B*5102 and HLA-B*3701/B*4601 allele, respectively. Our findings provide evidence to support that other genetic markers or nongenetic factors could contribute to the susceptibility of PHT-induced SJS, except for HLA-B*1502 allele. Further studies are encouraged to investigate the genetic link with PHT-induced serious skin reactions in future.