NAT2*61 is assigned unknown function based on a lack of evidence. NAT2*61 is characterized by the core SNVs c.506A>G (p.Y169C) 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 literature describing function for c.506A>G (p.Y169C). Four out of nine variant effect predictors tested by CPIC staff predict that c.506A>G (p.Y169C) impairs protein function.