CYP2D6*19 is assigned no function based on limited evidence. CYP2D6*19 is defined by a four base deletion resulting in a frameshift and yielding a nonfunctional enzyme (9241659). Therefore, consensus among experts was no function with an activity value of 0 based on limited evidence as it was determined the phenotypes containing this allele would be clinically distinct from phenotypes comprising normal and decreased function alleles.