Development and Analytical Validation of a Laboratory-Customized TaqMan-MGB Probe Method for CYP2C19 Genotyping.

Area of Science:

• Pharmacogenomics
• Molecular Diagnostics
• Clinical Chemistry

Background:

• Cytochrome P450 family 2 subfamily C member 19 (CYP2C19) genetic variations significantly impact drug metabolism.
• Established TaqMan genotyping for CYP2C19*2 and CYP2C19*17 exists, but open-source, locally adaptable methods are valuable for validation and application.
• This study focused on developing and validating a customized, open-sequence TaqMan-MGB assay for specific CYP2C19 polymorphisms.

Purpose of the Study:

• To develop and analytically validate a laboratory-customized, open-sequence TaqMan-MGB assay.
• To detect the CYP2C19*2 (rs4244285) and CYP2C19*17 (rs12248560) genetic variants.
• To provide a locally implementable workflow for genotyping.

Main Methods:

• Design of specific primers and allele-specific TaqMan-MGB probes.
• Evaluation of assay performance, including specificity, analytical sensitivity, limit of detection (LOD), and repeatability.
• Preliminary clinical concordance assessment using 20 dried blood spot (DBS) samples, with Sanger sequencing as the reference method.

Main Results:

• The assay successfully differentiated genotypes for CYP2C19*2 and CYP2C19*17 in clinical samples.
• Candidate LODs were determined as 1.17 × 10^2 copies/μL for CYP2C19*2 and 0.94 × 10^3 copies/μL for CYP2C19*17.
• 100% sample-level concordance with Sanger sequencing was observed for the 20 DBS samples, with coefficients of variation below 10% for repeatability.

Conclusions:

• The developed TaqMan-MGB assay demonstrated acceptable preliminary analytical specificity, sensitivity, and repeatability.
• The assay's strength lies in its customizable, open-sequence design and DBS compatibility.
• Further validation with larger, diverse cohorts including all relevant genotypes is necessary for routine clinical use.