CYP2D6*143 is assigned no function based on limited evidence. CYP2D6*143 is defined by a premature stop codon predicted to yield truncated protein and thus be nonfunctional. A subject sequenced as CYP2D6*143/*144 had a risperidone/9-hydroxy-risperidone ratio that was higher (indicating lower activity) compared to that found in subjects with two no function alleles(33998274). Therefore, consensus among experts was no function.