NAT2*4 is no longer considered as the reference allele: Alleles carrying c.803G>A as their only amino acid changing SNV will be called as *4 according to the new nomenclature. This includes the former NAT2*4 reference allele of sequence X14672.1, now considered a variant and listed as NAT2*4.001. Although this will no longer be used as a reference, it is considered to be functionally equivalent to NAT2*1.001 (formerly NAT2*12A) and may still be used to compare the enzymatic or structural properties of polymorphic NAT2 proteins.