Klin Farmakol Farm. 2026;40(3):176-180 | DOI: 10.36290/far.2026.027

Genotype-phenotype correlation of CYP2C19: phenoconversion, population-specific characteristics, and modern sequencing approaches in personalised pharmacotherapy

Jan Soukop, Marek Pecha, Pavel Anzenbacher

Ústav farmakologie Fakultní nemocnice Olomouc a Lékařské fakulty Univerzity Palackého v Olomouci

Cytochrome P450 2C19 (CYP2C19) plays a key role in the metabolism of many commonly used medicines, including clopidogrel, antidepressants and proton pump inhibitors. Although CYP2C19 genotyping is a useful tool in personalised medicine, its clinical application is often complicated by the phenomenon of phenoconversion, in which the patient's actual phenotype (enzymatic activity) does not correspond to the genetically predicted phenotype. This phenomenon is most commonly caused by drug-drug interactions involving CYP inducers and inhibitors or by patient comorbidi­ties. In Central European populations, the distribution of alleles is characterised by a below-average prevalence of the loss-of-function allele *2 (approximately 7-8%) and an above-average prevalence of the gain-of-function allele *17 (approximately 29%), increasing the risk of misinterpretation of pharmacogenetic findings. Conventional PCR methods detect only predefined variants and do not allow so-called haplotype phasing. Next-generation sequencing (NGS) and whole-exome sequencing (WES) overcome these limitations, albeit at the cost of greater interpretative and organisational complexity. Knowledge of local population-specific characteristics and the risk of phenoconversion is essential for the safe individualisation of pharmacotherapy.

Keywords: CYP2C19, pharmacogenetics, genotype, phenotype, phenoconversion, drug interactions, next-generation sequencing, personalised medicine.

Received: May 25, 2026; Revised: June 22, 2026; Accepted: July 1, 2026; Published: October 14, 2026  Show citation