Genetics of severe drug hypersensitivity reactions in Han Chinese
Drug hypersensitivity, an immune-related idiosyncratic ad-verse reaction, was historically referred to as being unpre-dictable. However, recent studies in Han Chinese have re-vealed that several types of severe drug hypersensitivity reactions have a strong genetic predisposition and might be predicted, particularly with the use of the genes coding for major histocompatibility complex (MHC), a key mole-cule for immune response. The genetic predisposition is drug-and phenotype-specific, HLA-B*1502 is associated with carbamazepine-induced Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), and HLA-B*5801 with allopurinol-SJS/TEN/hypersensitivity syndrome. These genetic associations are not limited to the Han Chinese, and their significance in other ethnic populations depends on the allele frequency of the populations. The genetic studies in Han Chinese support the concept that MHC-restricted presentation of drug is involved in the pathogenesis of im-mune-mediated severe drug hypersensitivity reactions. These genetic markers have the potential to be used for further development of tests to identify individuals at risk for these drug-related life-threatening conditions, as well as for an increased understanding of the pathogenesis of these clinical syndromes.© 2007 by S. Karger AG, Basel. All rights reserved.