CYP2D6*38 is assigned no function based on limited evidence in a heterozygous subject. CYP2D6*38 was identified in a heterozygous subject with CYP2D6 *4/*38 genotype demonstrating poor metabolism with a debrisoquine substrate (9918137). CYP2D6*38 is defined by a four base pair deletion resulting in a frameshift. 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.