Mitochondrial DNA Analysis in the United Arab Emirates

Abstract

Mitochondrial DNA (mtDNA) analysis has emerged as a powerful investigation tool in forensic science over the past few decades. The unique properties of mtDNA, such as maternal inheritance and high copy number, make it particularly useful in cases where nuclear DNA is rapidly degraded or insufficient. Until recently, routine analysis has been limited to the control region; however, recent advances in sequencing technologies have enabled comprehensive analysis of the entire mitochondrial genome. The development of massively parallel sequencing (MPS) technologies has revolutionized the field, allowing for high-throughput sequencing with enhanced discrimination power and cost efficiency.

This study aimed to develop a relevant high quality population database for frequency estimation and to evaluate the implementation of whole mitochondrial genome sequencing in forensic science within a selective populatiom in the United Arab Emirates (UAE).

A population database consisting of 610 whole mitogenome haplotypes was developed, encompassing 510 samples from UAE nationals, 50 samples from Indians, and 50 samples from Pakistanis. The results show that each sample exhibited a set of SNPs variations, which were used to define individual haplotypes and subsequently assign each sample to its closest haplogroup.

The Precision ID Whole mtDNA Genome Panel Kit was utilized to implement the whole mitochondrial genome sequencing. The overall haplotype diversity was comparable to other global populations, with minor improvements in haplotype diversity observed when compared to control region analysis alone. The total number of haplotypes was 445 for the Emiratis, 49 for the Indians and 50 for the Pakistanis. The unique haplotypes reported 400 individuals out of the 510 Emirati mDNA sequences. For Indians, 48 individuals expressed unique haplotypes. Last, for Pakistanis, 50 individuals had unique haplotypes. Those numbers represented 78.43% unique haplotypes within the dataset of this study, while the remaining 21.57% were shared haplotypes for Emiratis. For the Indian population, 96% of the individuals had unique haplotypes, with only two individuals having a shared. All the Pakistani samples displayed unique haplotypes, accounting for 100% of their dataset.

Haplogroups for the obtained haplotypes were assigned using various tools, including online EMPOP and Haplogrep, and Converge Software. In the Emirati dataset, the H haplogroup was the most common at 15.49%, followed by Haplogroup U at 13.73%. In the Pakistani dataset, Haplogroup M is predominant, accounting for 50% of the population, followed by Haplogroup U at 22%. Similarly, in the Indian dataset, Haplogroup M is also the most prevalent, comprising 44% of the samples, with Haplogroup U appearing in 22% of the population. Emiratis had 241 different haplogroups, while Pakistanis and Indians showed 42 and 40 haplogroups, respectively.

Initially, a cohort of 93 biological specimens (blood reference samples) underwent sequencing of the mitochondrial control region via the Sanger method. Subsequently, these identical specimens were subjected to MPS utilizing Ion Torrent technologies.

Complete concordance was achieved between the datasets generated by these two sequencing methodologies.

The study was extended to implement this technology to 56 casework samples and 56 bone samples, to evaluate its robustness. Profiles were obtained from all samples, although some were classified as partial.
In conclusion, the results from the study represent a crucial step toward the implementation of mtDNA analysis in forensic science in the UAE, enhancing the capability to analyse previously unusable samples and improving responses to missing persons cases and mass disasters. The successful integration of MPS technologies into forensic workflows will significantly advance our understanding of the application of mitochondrial DNA analysis and its potential in the context of the UAE.