NAT2*54 is assigned uncertain function based on inadequate evidence. NAT2*54 is characterized by the core SNVs c.29T>C (p.I10T) and c.803G>A (p.R268K). c.803G>A (p.R268K) defines NAT2*4, formerly considered the reference allele, which has repeatedly shown increased function in vivo and in vitro. Published in silico modeling predicts that c.29T>C (p.I10T) does not alter NAT2 protein function (19909761). However, five out of nine variant effect predictors tested by CPIC staff predict that c.29T>C (p.I10T) impairs NAT2 protein function. Additionally, a structure-based computational prediction tool predicts that c.29T>C (p.I10T) decreases NAT2 protein stability which could lead to decreased function.