Development and Preliminary Evaluation of a Pharmacogenetic Panel for Risk Stratification of Liver Injury in Polypharmacy

Background: Although drug-induced liver injury (DILI) remains a concern in polypharmacy, especially in older cardiovascular patients, pharmacogenetic markers are not routinely used for DILI risk prediction. Genome-wide polygenic scores aggregate thousands of variants but remain costly for routine care. In this study, we developed and preliminarily evaluated a PCR-based pharmacogenetic panel targeting key drug metabolism and transport genes for hepatotoxicity risk stratification in polypharmacy patients. Methods: A real-time PCR panel covering 12 polymorphisms in NAT2, CYP2C9, UGT2B7, ABCB1, and SLCO1B1 was developed using fluorescent probe melting. Autopsy liver samples and clinical data were obtained from 47 patients over 50 years old who had taken five or more cardiovascular drugs for at least six months. Liver morphology was assessed histomorphometrically using METAVIR fibrosis/activity scores and a composite Hepatic Lesion Index (HLI), while an integrated pharmacogenetic (PGx) score combined CYP2C9 metabolizer status, NAT2 acetylation, and SLCO1B1/OATP1B1 transport function. Results: Significant fibrosis (METAVIR F ≥ 2) was found in 36.2% of patients, and no liver was entirely histologically normal. Carriage of the NAT2 rs1799931 minor allele was strongly associated with a higher HLI (median 7.0 vs. 4.0; adjusted p = 0.00013) and was the only independent predictor of fibrosis stage in multivariable regression (OR = 16.36; p = 0.00268). Conclusions: A limited, accessible five-gene panel identified clinically relevant variability in hepatotoxicity-associated genetic profiles among polypharmacy patients, with NAT2 status showing the strongest association with liver injury severity. These preliminary findings support further validation of targeted pharmacogenetic screening as a potentially scalable and cost-effective alternative to genome-wide approaches for assessing hepatotoxicity susceptibility in vulnerable populations.