Medical Genetics Commons^™

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

Manuscripts, Articles, Book Chapters and Other Papers

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 …

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

Manuscripts, Articles, Book Chapters and Other Papers

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 …

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

Manuscripts, Articles, Book Chapters and Other Papers

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, …

Cyp2d7 Sequence Variation Interferes With Taqman Cyp2d6 (*) 15 And (*) 35 Genotyping., Amanda K. Riffel, Mehdi Dehghani, Toinette Hartshorne, Kristen C. Floyd, J Steven Leeder, Kevin P. Rosenblatt, Andrea Gaedigk

Manuscripts, Articles, Book Chapters and Other Papers

TaqMan™ genotyping assays are widely used to genotype CYP2D6, which encodes a major drug metabolizing enzyme. Assay design for CYP2D6 can be challenging owing to the presence of two pseudogenes, CYP2D7 and CYP2D8, structural and copy number variation and numerous single nucleotide polymorphisms (SNPs) some of which reflect the wild-type sequence of the CYP2D7 pseudogene. The aim of this study was to identify the mechanism causing false-positive CYP2D6 (*) 15 calls and remediate those by redesigning and validating alternative TaqMan genotype assays. Among 13,866 DNA samples genotyped by the CompanionDx® lab on the OpenArray platform, 70 samples were identified as …