Medicine and Health Sciences Commons^™

In Vivo Characterization Of Cyp2d6*12, *29 And *84 Using Dextromethorphan As A Probe Drug: A Case Report., Andrea Gaedigk, Greyson P. Twist, Emily G. Farrow, Jennifer Lowry, Sarah E. Soden, Neil A. Miller

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CYP2D6*84 was first described in a Black South African subject, however, its function remains unknown. Astrolabe, a probabilistic scoring tool developed in our laboratory to call genotypes from whole genome sequence, identified CYP2D6*84 in a trio. The father presented with intermediate metabolism when challenged with the CYP2D6 probe drug dextromethorphan (DM/dextrorphan [DX] = 0.0839). Since his second allele, CYP2D6*12, is nonfunctional, the observed activity is derived by CYP2D6*84. This finding suggests that the allele's hallmark P267H causes decreased activity toward DM and that this allele should receive a value of 0.5 for Activity Score calculations. The mother's DM/DX of 0.0543 …

Impact Of Cyp2d6 Genotype On Amitriptyline Efficacy For The Treatment Of Diabetic Peripheral Neuropathy: A Pilot Study., Mamoonah Chaudhry, Marco Alessandrini, Jacobus Rademan, Tyren M. Dodgen, Francois E. Steffens, Danie G. Van Zyl, Andrea Gaedigk, Michael S. Pepper

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AIM: Therapy with low-dose amitriptyline is commonly used to treat painful diabetic peripheral neuropathy. There is a knowledge gap, however, regarding the role of variable CYP2D6-mediated drug metabolism and side effects (SEs). We aimed to generate pilot data to demonstrate that SEs are more frequent in patients with variant CYP2D6 alleles.

METHOD: To that end, 31 randomly recruited participants were treated with low-dose amitriptyline for painful diabetic peripheral neuropathy and their CYP2D6 gene sequenced.

RESULTS: Patients with predicted normal or ultra-rapid metabolizer phenotypes presented with less SEs compared with individuals with decreased CYP2D6 activity.

CONCLUSION: Hence, CYP2D6 genotype contributes to …

Prediction Of Cyp2d6 Phenotype From Genotype Across World Populations., Andrea Gaedigk, Katrin Sangkuhl, Michelle Whirl-Carrillo, Teri Klein, J Steven Leeder

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PURPOSE: Owing to its highly polymorphic nature and major contribution to the metabolism and bioactivation of numerous clinically used drugs, CYP2D6 is one of the most extensively studied drug-metabolizing enzymes and pharmacogenes. CYP2D6 alleles confer no, decreased, normal, or increased activity and cause a wide range of activity among individuals and between populations. However, there is no standard approach to translate diplotypes into predicted phenotype.

METHODS: We exploited CYP2D6 allele-frequency data that have been compiled for Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines (>60,000 subjects, 173 reports) in order to estimate genotype-predicted phenotype status across major world populations based on …

Long-Read Single Molecule Real-Time Full Gene Sequencing Of Cytochrome P450-2d6., Wanqiong Qiao, Yao Yang, Robert Sebra, Geetu Mendiratta, Andrea Gaedigk, Robert J. Desnick, Stuart A. Scott

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The cytochrome P450-2D6 (CYP2D6) enzyme metabolizes ∼25% of common medications, yet homologous pseudogenes and copy number variants (CNVs) make interrogating the polymorphic CYP2D6 gene with short-read sequencing challenging. Therefore, we developed a novel long-read, full gene CYP2D6 single molecule real-time (SMRT) sequencing method using the Pacific Biosciences platform. Long-range PCR and CYP2D6 SMRT sequencing of 10 previously genotyped controls identified expected star (*) alleles, but also enabled suballele resolution, diplotype refinement, and discovery of novel alleles. Coupled with an optimized variant-calling pipeline, CYP2D6 SMRT sequencing was highly reproducible as triplicate intra- and inter-run nonreference genotype results were completely concordant. Importantly, …

Constellation: A Tool For Rapid, Automated Phenotype Assignment Of A Highly Polymorphic Pharmacogene,, Greyson P. Twist, Andrea Gaedigk, Neil A. Miller, Emily G. Farrow, Laurel K. Willig, Darrell L. Dinwiddie, Josh E. Petrikin, Sarah E. Soden, Suzanne Herd, Margaret Gibson, Julie A. Cakici, Amanda K. Riffel, J Steven Leeder, Deendayal Dinakarpandian, Stephen F. Kingsmore

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An important component of precision medicine-the use of whole-genome sequencing (WGS) to guide lifelong healthcare-is electronic decision support to inform drug choice and dosing. To achieve this, automated identification of genetic variation in genes involved in drug absorption, distribution, metabolism, excretion and response (ADMER) is required. CYP2D6 is a major enzyme for drug bioactivation and elimination. CYP2D6 activity is predominantly governed by genetic variation; however, it is technically arduous to haplotype. Not only is the nucleotide sequence of CYP2D6 highly polymorphic, but the locus also features diverse structural variations, including gene deletion, duplication, multiplication events and rearrangements with the nonfunctional, …