Human CYP2D6*44 allele is located in the vicinity of 22q13.1 and is approximately 4 kb in length. This allele, a variant form of the CYP2D6 wild-type allele, encodes cytochrome P450 2D6*44 protein. The CYP2D6*44 allele exhibits a clinically-relevant SNP (g.2950G>C) in the intron 6 donor splice junction that results in a splicing defect. This alteration abolishes the enzymatic activity of the cytochrome P450 2D6*44 protein. [ ]