ClinVar Genomic variation as it relates to human health

This allelic variant is also known as CYP2D6*2 or CYP2D6L. In a family in which 2 sibs and their father had MRs of less that 0.02 (ultrarapid phenotype, see 608902), Johansson et al. (1993) found 12 extra copies of the CYP2D6 gene inherited in an autosomal dominant pattern; in a second family in which 2 sibs had MRs of less than 0.1, the authors found 2 extra copies of the CYP2D6 gene. All affected individuals had a variant CYP2D6 gene, termed CYP2D6L, which contained 2 amino acid substitutions: a 2938C-T transition in exon 6, resulting in an arg296-to-cys (R296C), and a 4268G-to-C transversion in exon 9, resulting in a resulting in a ser486-to-thr (S486T) substitution. The MR of individuals with 1 copy of the CYP2D6L gene did not differ from those with the wildtype gene, but there was a correlation between decreased MR and increased copies of the CYP2D6L gene. Panserat et al. (1994) identified the R296C and S486T changes as 2 major CYP2D6 allozymes in extensive metabolizers (wildtype). Residue 296 falls within a presumed substrate recognition site, and residue 486 lies in the vicinity of the heme binding site. (less)