HLA-B and mitochondrial DNA depletion syndrome 4a: Similarly, abacavir hypersensitivity syndrome (AHS), a severe systemic hypersensitivity reaction to the antiretroviral drug abacavir and drug-induced liver injury mediated by the antibiotic flucloxacillin, are associated with HLA-B*57:0110,11, whilst the closely related HLA-B*57:03, containing two amino acid substitutions in the antigen-binding cleft shows no association.