Divergent Phenotypes, Actionable Genotypes, and Phenoconversion in a German Psychiatric Inpatient Population: Results from the FACT-PGx Study

Background and objectivesGenetic polymorphisms of CYP2D6 and CYP2C19 affect both the effectiveness and the occurrence of side effects of many antidepressants. By drug-drug-gene interactions (also referred to as phenoconversion), the phenotype of the patient can be changed. Both pharmacogenetic testing, drug-drug, and drug-drug-gene interaction checks are essential to individualize the dose of the antidepressant or start an alternative drug in accordance with the pharmacogenetic guidelines. The aim of this study was to analyze the frequency of divergent phenotypes (i.e. divergent from the common phenotypes considered normal), of phenoconversion (a genotype–phenotype mismatch), and of actionable genotypes (genotypes where a prescribing change may be indicated) in psychiatric inpatients with a depressive disorder.