PharmVar GeneFocus: NAT2-Genetic Variation and Updated Nomenclature.

The Pharmacogene Variation Consortium (PharmVar) provides nomenclature for the highly polymorphic human N-acetyltransferase 2 (NAT2) gene. NAT2 metabolizes several clinically used drugs including isoniazid, hydralazine, amifampridine, procainamide, and sulfonamides such as dapsone, and also some highly carcinogenic arylamines. Systematic nomenclature describing NAT2 variation is essential for pharmacogenetic testing, genotype interpretation, and translation to phenotype in research and clinical settings. This GeneFocus provides an overview of NAT2 variation and describes important changes to its star allele-based nomenclature that were made as it was transitioned to PharmVar in March 2024. We also highlight and discuss challenges regarding the characterization of allelic variation and determination of allele frequencies across world populations. The "new" NAT2 PharmVar nomenclature is utilized by ClinPGx (formerly PharmGKB) and the Clinical Pharmacogenetics Implementation Consortium (CPIC).