HLA-B*5801 testing: Is it time to consider mandatory testing prior to prescribing allopurinol in Singapore?

Stevens-Johnsons Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are severe, life- threatening mucocutaneous reactions that most commonly occur as drug-related reactions.1 In recent years, several risk factors for the develop- ment of SJS/TEN, such as genetic factors, have been identified. Notably, carriers of the HLA-B*5801 and HLA-B*1502 alleles have an increased risk of SJS/TEN with the use of allopurinol and carbamazepine, respectively.2 Consequently, much debate has arisen over the utility of pharmacogenomics in preventing SJS/ TEN. We will discuss the evidence surrounding genetic testing in the prevention of allopurinol- induced SJS/TEN, with the aim of highlighting the potential value of pre-testing.