Review For reprint orders, please contact: reprints@futuremedicine.com Pharmacogenomics in the Nigerian population: the past, the present and the future Oluseye O Bolaji* ,1 , Ayorinde Adehin 1,2 & Babatunde A Adeagbo 1 1 Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Nigeria 2 Institute of Biomedical & Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, PR China *Author for correspondence: Tel.: +234 803 720 0119; obolaji@oauife.edu.ng The Nigerian population exhibits huge ethnic and genetic diversity, typical of African populations, which can be harnessed for improved drug-response and disease management. Existing data on genes relevant to drug response, so far generated for the population, indeed confrm the prevalence of some clinically signifcant pharmacogenes. These reports detail prevailing genetic alleles and metabolic phenotypes of vital drug metabolizing monooxygenases, transferases and drug transporters. While the utilization of existing pharmacogenomic data for healthcare delivery remains unpopular, several past and on-going studies suggest that a future shift toward genotype-stratifed dosing of drugs and disease management in the population is imminent. This review discusses the present state of pharmacogenomics in Nigeria and the potential benefts of sustained research in this feld for the population. First draft submitted: 28 March 2019; Accepted for publication: 28 June 2019; Published online: 27 August 2019 Keywords: adverse drug reactions • drug metabolism • drug transporters • Nigeria • pharmacogenomics Dating back several decades, studies in the field of pharmacogenomics/pharmacogenetics have devoted efforts toward unraveling the intricate relationship between drug response and the human genome. This had become important in the wake of serious, and at times fatal, dose-independent and preventable adverse drug reactions (ADRs), and poor clinical responses at different stages of drug development [1,2]. Reviews of data in the last two decades suggest that ADRs may be responsible for about 197,000 deaths annually in the EU [3]. For example, in 2016 alone, 1,238,178 cases of ADR were captured in the EU pharmacovigilance report [4]. A retrospective study of variable drug response in the USA has also estimated that ADRs account for about 6.7% of hospital admissions annually [5]. Studies of the genetic predictors of drug efficacy and preventable ADRs had necessarily gained prominence not only for drug safety, but also because of the huge cost of such unintended drug actions on healthcare systems and drug development processes. These studies, at the early stage, had involved candidate–gene association with unfavorable drug responses. However, sustained improvements in the throughput of genotyping technology and genomic data processing resulted in the replacement of the initial candidate–gene association approach with genome-wide association studies in efforts aimed at identifying new genomic determinants of variable drug response [6,7]. The end goal of these pharmacogenomic studies was to provide a template that ensures the tailored dosing of drugs, for optimum efficacy and safety, based on individual phenotype [8]. A translational application of pharmacogenomic data, and the benefits thereof, draws from the ability of such data to provide information on mutations indicative of disease susceptibility, drug efficacy or toxicity. The genome diversity that characterizes the populations of the world, however, necessitates that more populations be studied for a comprehensive understanding of gene-to-drug–response relationships. While several studies have been undertaken (and several others ongoing) in non-African populations, very little is still known about African populations where several unknown genetic determinants of preventable ADRs may yet be locked away. This draws from the fact that African populations are characterized by hugely diverse genomes, mainly due to a deep population structure Pharmacogenomics (2019) 20(12), 915–926 ISSN 1462-2416 915 10.2217/pgs-2019-0046 C  2019 Future Medicine Ltd