NAT2*30 is assigned decreased function based on moderate evidence. The NAT gene nomenclature committee has historically assigned acetylation activity to alleles as either "rapid" or "slow", classifying the NAT2*30 allele as "slow" . Under the CPIC allele function terminology, slow acetylation alleles are categorized as "Decreased Function". NAT2*30 is characterized by the core SNVs: c.341T>C (p.I114T), 590G>A (p.R197Q), and c.803G>A (p.R268K). c.803G>A defines NAT2*4, formerly considered the reference allele, which has repeatedly exhibited increased function in vivo and in vitro. c.341T>C (defining NAT2*5) and c.590G>A (defining NAT2*6) have both repeatedly shown decreased NAT2 N-acetylation in numerous in vivo and in vitro studies. NAT2*30 was reported in a clinical NAT2 phenotyping study using caffeine as a probe drug; 4 individuals heterozygous for NAT2*30 exhibited decreased acetylation of caffeine metabolites (15558239 ). An additional in vitro study showed that NAT2*5 (which contains the core SNV c.341T>C, p.I114T) is subjected to enhanced protein degradation by the proteasome (15564878). Thus, NAT2*30 would presumably be degraded in the same manner. Five and seven out of nine variant effect predictors tested by CPIC staff predict that c.341T>C (p.I114T) and c.590G>A (p.R197Q) impair protein function, respectively, while eight out of eight predictors tested by CPIC staff predict that c.803G>A (p.R268K) is neutral/tolerated for protein function. Though c.341T>C and:c.590G>A are both definitively attributed to decreased function individually, the combinatorial effects of having both variants present in the same allele are uncertain.