Validation of a multi-gene qPCR-based pharmacogenomics panel across major ethnic groups in Singapore and Indonesia

Background: With up to 70% of adverse drug reactions (ADRs) having high genetic associations, the clinical utility of pharmacogenomics (PGx) has been gaining traction. Nala PGx Core is a multi-gene qPCR-based panel that comprises 18 variants and 2 CYP2D6 Copy Number markers across 4 pharmacogenes - CYP2C9, CYP2C19, CYP2D6 and SLCO1B1. Objectives: In this study, we validated the performance of Nala PGx Core against benchmark methods, on the Singaporean and Indonesian populations. Additionally, we examined the allele and diplotype frequencies across 5 major ethnic groups present in these populations namely, Indonesians, Chinese, Malays, Indians and Caucasians. Methods: Human gDNA samples, extracted from the buccal swabs of 246 participants, were tested on Nala PGx Core and two chosen benchmarks, Agena VeriDose Core and CYP2D6 Copy Number Variation (CNV) Panel, and TaqMan DME Genotyping Assays. Performance was evaluated based on assay robustness, precision and accuracy at the genotype- and diplotype-level. Results: Nala PGx Core demonstrated high genotype- and diplotype-level call rates of >97% and >95% respectively in CYP2D6, and 100% for CYP2C9, CYP2C19 and SLCO1B1. A precision rate of 100% was observed on both intra- and inter-precision studies. Variant-level concordance to the benchmark methods was >96.9% across all assays, which consequently resulted in a diplotype-level concordance of >94.7% across CYP2C9, CYP2C19 and CYP2D6. Overall, the allele frequencies of CYP2D6*10 and CYP2D6*36 were higher in our cohort as compared to previous records. Notably, CYP2D6 copy number variation (CNV) analysis demonstrated a CYP2D6 *10/*36 frequency of 26.5% amongst the Indonesian cohort. Conclusion: Nala PGx Core produced robust and accurate genotyping when compared to other established benchmarks. Furthermore, the panel successfully characterized alleles of clinical relevance in the Singaporean and Indonesian populations such as CYP2D6*10 and CYP2D6*36, suggesting its potential for adoption in clinical workflows regionally.