NAT2*52 is assigned decreased function based on moderate evidence. NAT2*52 is characterized by the core SNVs c.518A>G (p.K173R), c.590G>A (p.R197Q) 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. There is no experimental evidence describing function for c.518A>G (p.K173R). Nine out of nine variant effect predictors tested by CPIC staff predict that c.518A>G (p.K173R) does not impair protein function. Similarly, published in silico analysis indicates that c.518A>G does not alter protein function (29273096). c.590G>A (p.R197Q) defines NAT2*6 which has been extensively studied, exhibiting decreased N-acetyltransferase activity both in vivo and in vitro. Similarly, seven out of nine variant effect predictors tested by CPIC staff predict that c.590G>A (p.R197Q) impairs protein function. Thus, NAT2*52 is assigned decreased function based on c.590G>A. While c.518A>G is not predicted to impair protein function, the combinatorial effects associated with c.590G>A and c.518A>G are uncertain.