Identification of Novel CYP2D7-2D6 Hybrids: Non-Functional and Functional Variants.

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Gaedigk A, Jaime LK, Bertino JS Jr, Berard A, Pratt VM, Bradfordand LD, Leeder JS

Identification of Novel CYP2D7-2D6 Hybrids: Non-Functional and Functional Variants.

Front Pharmacol. 2010 Oct 4;1:121. doi: 10.3389/fphar.2010.00121. eCollection 2010.

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21833166 [ View in PubMed

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Abstract

Polymorphic expression of CYP2D6 contributes to the wide range of activity observed for this clinically important drug metabolizing enzyme. In this report we describe novel CYP2D7/2D6 hybrid genes encoding non-functional and functional CYP2D6 protein and a CYP2D7 variant that mimics a CYP2D7/2D6 hybrid gene. Five-kilobyte-long PCR products encompassing the novel genes were entirely sequenced. A quantitative assay probing in different gene regions was employed to determine CYP2D6 and 2D7 copy number variations and the relative position of the hybrid genes within the locus was assessed by long-range PCR. In addition to the previously known CYP2D6*13 and *66 hybrids, we describe three novel non-functional CYP2D7-2D6 hybrids with gene switching in exon 2 (CYP2D6*79), intron 2 (CYP2D6*80), and intron 5 (CYP2D6*67). A CYP2D7-specific T-ins in exon 1 causes a detrimental frame shift. One subject revealed a CYP2D7 conversion in the 5'-flanking region of a CYP2D6*35 allele, was otherwise unaffected (designated CYP2D6*35B). Finally, three DNAs revealed a CYP2D7 gene with a CYP2D6-like region downstream of exon 9 (designated CYP2D7[REP6]). Quantitative copy number determination, sequence analyses, and long-range PCR mapping were in agreement and excluded the presence of additional gene units. Undetected hybrid genes may cause over-estimation of CYP2D6 activity (CYP2D6*1/*1 vs *1/hybrid, etc), but may also cause results that may interfere with the genotype determination. Detection of hybrid events, "single" and tandem, will contribute to more accurate phenotype prediction from genotype data.

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*13	Not Available	CYP2D7/2D6 hybrid gene structure	ADR Inferred	Increased risk of slow heart rate (bradycardia)	Details
Venlafaxine	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*13	Not Available	CYP2D7/2D6 hybrid gene structure	Effect Inferred	Poor drug metabolizer, lower dose requirements, nausea, vomiting and diarrhea	Details
Codeine	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*13	Not Available	CYP2D7/2D6 hybrid gene structure	Effect Inferred	Poor drug metabolizer, lower dose requirements	Details
Amitriptyline	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*13	Not Available	CYP2D7/2D6 hybrid gene structure	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*13	Not Available	CYP2D7/2D6 hybrid gene structure	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*13	Not Available	CYP2D7/2D6 hybrid gene structure	Effect Inferred	Poor drug metabolizer, lower dose requirements	Details
Nortriptyline	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*13	Not Available	CYP2D7/2D6 hybrid gene structure	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*13	Not Available	CYP2D7/2D6 hybrid gene structure	Effect Inferred	Poor response to drug treatment, shorter time to relapse	Details
Desipramine	Cytochrome P450 2D6 Gene symbol: CYP2D6 UniProt: P10635	CYP2D6*13	Not Available	CYP2D7/2D6 hybrid gene structure	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*13	Not Available	CYP2D7/2D6 hybrid gene structure	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*13	Not Available	CYP2D7/2D6 hybrid gene structure	Effect Inferred	Poor drug metabolizer, increased side effects.	Details