HLA alleles and drug hypersensitivity reactions.

The human leucocyte antigen (HLA) system is well known for its association with certain diseases such as ankylosing spondylitis, celiac disease and many others. More recently, severe and even fatal drug hypersensitivity reactions linked to particular HLA alleles have been discovered. The significance of these discoveries has led the European Medicines Agency (EMA) and its member state agencies to recommend HLA gene testing before initiation of drug treatment. To date, the following drugs have been identified as causing significant drug hypersensitivity reactions in patients who have the following HLA alleles: abacavir and HLA-B57:01, carbamazepine and HLA-B15:02/A31:01 and finally allopurinol and HLA-B58:01. This review will outline and discuss these three drugs and their associated HLA alleles as well as examine the pathogenesis of the drug hypersensitivity reactions.