New cytochrome P450 2D6*56 allele identified by genotype/phenotype analysis of cryopreserved human hepatocytes.

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Li L, Pan RM, Porter TD, Jensen NS, Silber P, Russo G, Tine JA, Heim J, Ring B, Wedlund PJ

New cytochrome P450 2D6*56 allele identified by genotype/phenotype analysis of cryopreserved human hepatocytes.

Drug Metab Dispos. 2006 Aug;34(8):1411-6. Epub 2006 May 5.

PubMed ID

16679388 [ View in PubMed

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Abstract

Genotype/phenotype analysis with human hepatocytes has identified a new inactive CYP2D6 allele, CYP2D6*56. Cryopreserved human hepatocytes from 51 livers were evaluated for CYP2D6 activity with dextromethorphan as the probe substrate. Hepatocyte lots that lacked CYP2D6 activity were further evaluated for CYP2D6 expression and known genetic variations, including CYP2D6*2, *3, *4, *5, *6, *7, *8, *9, *10, *11, *14, *15, *17, *18, *19, *20, *25, *26, *29, *30, *35, *40, *41, *43, and various multiple copy CYP2D6 alleles (*1xn, *2xn, and *4xn) by the AmpliChip CYP450 prototype microarray (Roche Molecular Systems, Inc., Branchburg, NJ). Two discrepancies were uncovered between the CYP2D6 genotype and activity by this approach. In one sample, a previously unreported 3201C 224 T transition in exon 7 resulted in Arg344(CGA) being replaced by a stop codon (TGA), resulting in a CYP2D6 enzyme lacking the terminal 153 amino acids. This allele was given the designation of CYP2D6*56 and the GenBank accession number DQ282162. The lack of CYP2D6 activity in cryopreserved hepatocytes and microsomes found in the second sample, despite a normal level of CYP2D6 expression and a genotype (*10/*1) predictive of normal CYP2D6 activity, was attributed to enzyme inactivation by an unknown metabolite. The identification and characterization of the CYP2D6*56 allele indicates that commercial cryopreserved human hepatocytes may provide a valuable means to rapidly identify genetic variations with functional relevance. This integrated approach of identifying alleles and examining allele relationships to gene expression and function could be of tremendous value to understanding the mechanism responsible for functional differences in gene variation. The commercial availability of human cryopreserved hepatocytes also makes this potential readily available to any who are interested in it, not just those with access to private liver banks.

DrugBank Data that Cites this Article

Pharmaco-genomics

Drug	Interacting Gene/Enzyme	Allele name	Genotypes	Defining change(s)	Type(s)	Description	Details
Metoprolol	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*56	Not Available	3201C>T (rs72549347)	ADR Inferred	Increased risk of slow heart rate (bradycardia)	Details
Venlafaxine	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*56	Not Available	3201C>T (rs72549347)	Effect Inferred	Poor drug metabolizer, lower dose requirements, nausea, vomiting and diarrhea	Details
Codeine	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*56	Not Available	3201C>T (rs72549347)	Effect Inferred	Poor drug metabolizer, lower dose requirements	Details
Amitriptyline	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*56	Not Available	3201C>T (rs72549347)	Effect Inferred	Poor drug metabolizer, lower dose requirements, higher risk for adverse side effects	Details
Imipramine	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*56	Not Available	3201C>T (rs72549347)	Effect Inferred	Poor drug metabolizer, lower dose requirements, higher risk for adverse side effects	Details
Dextromethorphan	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*56	Not Available	3201C>T (rs72549347)	Effect Inferred	Poor drug metabolizer, lower dose requirements	Details
Nortriptyline	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*56	Not Available	3201C>T (rs72549347)	Effect Inferred	Poor drug metabolizer, lower dose requirements, higher risk for adverse side effects	Details
Tamoxifen	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*56	Not Available	3201C>T (rs72549347)	Effect Inferred	Poor response to drug treatment, shorter time to relapse	Details
Desipramine	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*56	Not Available	3201C>T (rs72549347)	Effect Inferred	Poor drug metabolizer, lower dose requirements, higher risk for adverse side effects	Details
Clomipramine	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*56	Not Available	3201C>T (rs72549347)	Effect Inferred	Poor drug metabolizer, lower dose requirements, higher risk for adverse side effects	Details
Atomoxetine	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*56	Not Available	3201C>T (rs72549347)	Effect Inferred	Poor drug metabolizer, increased side effects.	Details