The consensus of the CYP2D6 Genotype to Phenotype Standardization Project is just published in Clinical and Translational Science.
To address inconsistencies in the translation of CYP2D6 genotype to phenotype across guidelines (i.e. Clinical Pharmacogenetics Implementation Consortium (CPIC) and Dutch Pharmacogenetics Working Group (DPWG)) and between clinical genetic testing laboratories, CPIC recently conducted a modified-Delphi project to obtain consensus among a panel of international CYP2D6 experts for a uniform system for translating CYP2D6 genotype to phenotype (more information).
Modifications to CPIC’s prior system include downgrading the value assigned to the CYP2D6*10 allele for activity score calculation from 0.5 to 0.25 and changing the phenotype assignment for an activity score of 1 from normal metabolizer to intermediate metabolizer (see table of all previous and new phenotype groupings).
As a result changes have been made in the allele functionality table and the genotype to phenotype table and the impact on the CYP2D6-relevant guidelines is described on the individual guideline pages for atomoxetine, codeine, ondansetron and tropisetron, SSRIs, tamoxifen, and tricyclic antidepressants on the CPIC website.