Many pharmacogenomic biomarkers (PGBM) were identified and translated into 
clinical practice, affecting the usage of drugs via label updates. In this 
context, abacavir is one of the most brilliant examples of pharmacogenetic 
studies translated into clinical practice. Pharmacogenetic studies have revealed 
that abacavir HSRs are highly associated with the major histocompatibility 
complex class I. Large studies established the effectiveness of prospective 
HLA-B*57:01 screening to prevent HSRs to abacavir. Accordingly to these results 
the abacavir label has been modified: the European Medicines Agency (EMA) and 
the FDA recommend/suggested that the administration of abacavir must be preceded 
by a specific genotyping test. The HLA locus is extremely polymorphic, 
exhibiting many closely related alleles, making it difficult to discriminate 
HLA-B*57:01 from other related alleles, and a number of different molecular 
techniques have been developed recently to detect the presence of HLA-B*57:01. 
In this review, we provide a summary of the available techniques used by 
laboratories to genotype HLA-B*57:01, outlining the scientific and 
pharmacoeconomics pros and cons.