Genomic Landscape of the Mitochondrial Genome in the United Arab Emirates Native Population
In order to assess the genomic landscape of the United Arab Emirates (UAE) mitogenome, we sequenced and analyzed the complete genomes of 232 Emirate females mitochondrial DNA (mtDNA). We investigated the prevalence of haplogroups, genetic variation, heteroplasmy, and demography among the UAE native population with diverse ethnicity and relatively high degree of consanguinity. This study is significant because the Arabian Peninsula is an obliged link between East Africa and South Asia, serving as the primary link between Africa and Eurasia.
Geographic and Historical Context
There are two potential routes to the Arabian Peninsula, the northern and southern route, which is the first step out of Africa. The maternally inherited mtDNA has been used as a marker to relate lineages across geographic origins culminating in African haplogroup L and the Eurasian M and N, which shared a common route with the African L3. This radiation likely started the Eurasian colonization. Previous studies highlight the presence of autochthone M and N lineages along the southern route, suggesting that ancient migration via the southern route to the neighboring countries such as Oman and UAE is plausible.
Haplogroup Distribution and Genetic Diversity
We identified 968 mtDNA variants and high-resolution 15 haplogroups. Our results show that the UAE population received enough gene flow from Africa represented by the haplogroups L, U6, and M1. Furthermore, 16.8% of the population has an eastern provenance, depicted by the U haplogroup and the M Indian haplogroup (12%), whereas western Eurasian and Asian haplogroups (R, J, and K) represent 11 to 15%.
The following table summarizes the distribution of haplogroups identified in the study:
| Provenance | Associated Haplogroups | Estimated Frequency/Impact |
|---|---|---|
| African Gene Flow | L, U6, M1 | Significant gene flow |
| Eastern Provenance | U, M Indian | 16.8% (U) and 12% (M Indian) |
| Western Eurasian and Asian | R, J, K | 11% to 15% |
| Ancient Migration (Post-Africa) | L (N1 and X), L2a1d, L4, L3x1b | Oldest evolutionary histories |
Interestingly, we found an ancient migration present through the descendant of L (N1 and X) and other sub-haplogroups (L2a1d and L4) and (L3x1b), which is one of the oldest evolutionary histories outside of Africa. Our study of the UAE mitogenomes suggest that several maternal lineage migratory episodes liking African–Asian corridors occurred since the first modern human emerges out of Africa.
Demography and Selection Patterns
Our demographic analysis shows no population structure among populations, with low diversity and no population differentiation. In addition, we show that the transmission of mtDNA in the UAE population is under purifying selection with hints of diversifying selection on ATP8 gene. Demographic history, such as effective population size changes, short and long distance migrations, as well as admixture, shape the genetic variation. Last, our results show a population bottleneck, which coincides with the Western European contact (1400 ybp).