title: CYP2D6-related oxidation polymorphism in a Canadian Inuit population.
abstract: The xenobiotic oxidation polymorphism associated with cytochrome P450 2D6 (CYP2D6) was investigated in 152 genetically related and unrelated healthy Inuit subjects living in the High Arctic of eastern Canada. Phenotyping was based on HPLC determination of the CYP2D6-related dextromethorphan metabolic ratio in overnight urine samples after oral administration of 30 mg dextromethorphan hydrobromide. The log metabolic ratio was bimodally distributed, with three subjects classified as poor metabolizers (PMs). In subjects unrelated in the first degree, the incidence of the PM phenotype was 3 of 90 or 3.3%. PCR-based analyses of DNA for variants of the CYP2D6 gene demonstrated that the PMs of dextromethorphan had the defective allele CYP2D6*4. The estimated frequency of the CYP2D6*4 allele was 0.067-0.083, which is lower than the frequency in Caucasians but higher than the frequency in Oriental populations. The CYP2D6*3 and the CYP2D6*6 alleles were not detected in the Inuit population. The CYP2D6*10 allele was present in only four unrelated subjects, classified as extensive metabolizers (EMs), resulting in an estimated allele frequency of 0.022, which is much lower than in Oriental populations. This study demonstrated the existence of the CYP2D6 polymorphism in Canadian Inuit, while the frequencies of allelic variants of CYP2D6 point to the uniqueness of this population. Several important therapeutic drugs that are being prescribed in Arctic communities will have altered pharmacokinetics in PMs of CYP2D6.
authors.affiliation: Bureau of Drug Research, Drugs Directorate, Health Canada, Ottawa, ON, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Jurima-Romet
authors.forename: B C
authors.initials: BC
authors.lastname: Foster
authors.forename: W L
authors.initials: WL
authors.lastname: Casley
authors.forename: A
authors.initials: A
authors.lastname: Rode
authors.forename: P
authors.initials: P
authors.lastname: Vloshinsky
authors.forename: H S
authors.initials: HS
authors.lastname: Huang
authors.forename: S
authors.initials: S
authors.lastname: Geertsen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000483:Alleles; D002170:Canada; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics* / Q000378:metabolism; D003915:Dextromethorphan / Q000378:metabolism / Q000652:urine; D005260:Female; D005838:Genotype; D006801:Humans; D004930:Inuit / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011110:Polymorphism, Genetic
chemical_list: D003915:Dextromethorphan; D019389:Cytochrome P-450 CYP2D6