MATRILINEAL GENETIC DIVERSITY AND FORENSIC CHARACTERISATION OF HAUSA POPULATION IN NIGERIA

Abstract

Mitochondrial DNA (mtDNA) plays a crucial role in forensic science and population genetics, providing valuable insights into human evolution, ancestry, and disease susceptibility. African genetic diversity holds particular significance in understanding phylogeny, forensic investigations, and precision medicine. This study aims to investigate the control regions (HVR1 and HVR2) of mtDNA among a sample of 100 Hausa individuals from Nigeria. Buccal swabs were collected, and DNA extraction was performed performed using QiaGen DNA extraction kit according to manufacturer’s protocol, followed by quantification and purity assessment using Nanodrop One. PCR amplification was carried out using two primers for HVR1 and HVR2. The forward and reverse primers used for both the HVR1 and HVR2 were F-5’-TTA ACT CCA CCA TTA GCA CC-3’ and R-5’-CCT GAA GTA GGA ACC AGA TG-3’ and F-5' GGT CTA TCA CCC TAT TAA CCAC3' and R-5' CTG TTA AAA GTG CAT ACC GCCA3' respectively, followed by gel electrophoresis to ensure DNA quality and integrity. BIg dye terminator Sanger Type Sequencing was utilised for sequence analysis. Base calling and multiple alignments (ClustalW) were performed using BioEdit. AMOVA analysis was conducted using Arlequin, population admixture was assessed using STRUCTURE, phylogenetic tree construction utilised MEGA11, pairwise genetic comparisons were performed with SDT, and haplotype networks were created using PopArt and tcs. Of the total 100 individuals, 93 and 94 successful sequences were generated based on HVR and HVR2 primers respectively. The findings revealed significant within-population genetic variation based on AMOVA analysis in both HVR1 and HVR2, the within population variance was estimated at 99.69% and 96.69% in HVR1 and HVR2 respectively. The population admixture analysis revealed varying degrees of population subgrouping depending on the number of simulation runs. The phylogenetic tree and haplotype network analyses demonstrated complex genetic diversity among the Hausa iv population. The results underscore the importance of considering population-specific genetic markers for forensic investigations and population genetics studies in Nigeria. In addition, we downloaded the mitogenome sequences from the NCBI database of different global populations in order to make comparison with our genetic data. We downloaded from Southern Africa (Angola), Oceania (New Zealand) Tokelau population, South Asia (west Indian Caste), Central Europe (Switzerland), South America (Paraguay) and North America (Canada, Newfoundland) with accession numbers MF3812871-MF3813061, MT9282831-MT9282971, MK0439671-MK0439862, MT0790191-MT0790371, MH9818231-MH9818421 and MF5887941-MF5888111 respectively. We used Arlequin to conduct AMOVA and use the FST values generated to make a pairwise identity matrix between the populations using R statistical tool, SDT was used to make pairwise comparison of individual sequences, and STRUCTURE to make ancestral admixture within and between the population across the continents. We used 15-20 sequences from each of the continental populations. Markov Chain steps were set at 10,000, and a burn-in length of 10,000 was used with K replication values set at 6, and 3 iterations (Evanno et al., 2005). To determine which of the eighteen runs was best suited for inferring ancestral relationships among the study populations, a structure harvester was used (Earl & vonHoldt, 2012) The AMOVA result based on selected global populations across the continent indicated that the populations can be distinguished from one another with relative certainty based on their genetic sequence. More than 90% of the genetic variation is accounted for among the population with only a less than 10% within population variation. This has indicated that there is genetic variation between populations from Nigeria, Switzerland, New Zealand, West India, Angola, Paraguay and Canada. The overall FST value of above 0.9 indicated strong genetic diversity among the study population, thus inferring genetic variability. In addition, individual FST values that were used to generate a colour-coded matrix indicated genetic distinctiveness of the Nigerian population from the rest of the v world based on the mtDNA HVR2 data. However, it can be observed that statistical significance was only observed between Nigerian and Canadian population. Sequence Demarcation Tool indicated a pairwise individual genetic distance between the global population with the Nigerian population maintaining a high genetic diversity and distinctiveness from the rest of the population. However, the Angolan population that we assumed to show relationship with the Nigerian population had demonstrated a more genetic relatedness with the rest of the population. This can be attributed to mixed genetic traits between the Angolan and Portuguese populations that are still present in the country even after independence from the Portuguese colonisation. Based on the SDT figure, the South and North American population are furthest from the West African population, it is interesting that the Central European populations are placed closer to the West African populations. In our effort to determine shared ancestry between the West African and other continental populations, we observed a distinct ancestry of the Nigerian Hausa population from the rest of the world. The targeted Hausa population in our study were selected based on their historical importance in the Hausa kingdom. The targeted Hausa population were from ancient Hausa cities which could be the reason for such genetic uniqueness. The population has further elucidated the much reported high genetic diversity of the African population. This has further indicated the relevance of this population for forensic genetics. In conclusion, this study provides insights into the genetic diversity and structure of the Hausa population in Nigeria, as inferred from the analysis of mtDNA control regions. The identified patterns contribute to our understanding of the population's evolutionary history and can aid in forensic investigations and precision medicine approaches. Further research and expanded sampling are recommended to enhance the accuracy and robustness of population genetic studies in the region.