CYP2D6*6 is assigned no function based on strong evidence. CYP2D6*6 has been described in subjects demonstrating decreased metabolism of various CYP2D6 substrates (10022755, 7894499, 7951238, 7868129). CYP2D6*6 is defined by a single nucleotide deletion resulting in a frameshift and premature stop codon yielding a truncated and nonfunctional protein (7894499). Therefore, consensus among experts was no function with an activity value of 0 based on strong evidence.