TPMT*46 is assigned no function based on limited evidence. TPMT*46 is characterized by two SNVs: c.487C>T, p.R163C (the *33 variant) and c.644G>A, p.R215H (the *8 variant). TPMT*8 is assigned decreased function and TPMT*33 is assigned no function. Nine out of ten variant effect predictors tested by CPIC staff predict that c.644G>A (p.R215H) is neutral for protein function and seven out of ten predict that c.487C>T (p.R163C) impairs protein function. TPMT*46 is assigned no function based on the *33 SNV (c.487C>T; p.R163C).