Large-Scale Assessment of the Iranian population structure of Mitochondrial and Y-chromosome Haplogroups

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Abstract: The Iranian plateau, strategically positioned as a corridor for population diffusion across Eurasia, holds a pivotal role in elucidating the dynamics of human migrations originating from Africa around 60,000 years ago. Both prehistoric and historic movements of populations between Africa, Asia, and Europe may have been influenced by the unique geographical features of the Iranian plateau. Iran boasts ancient cultures and urban settlements predating some of the earliest civilizations, including the Neolithic revolution in neighboring Mesopotamia. Spanning from the Balkans and Egypt in the west to the Indus Valley in Pakistan and northern India in the southeast, the Iranian plateau encompasses a vast area characterized by incredible ethnocultural diversity. This region served as the origin for numerous mt-DNA/Y-DNA haplogroups that expanded to West Asia, Europe, Siberia, Central Asia, and South Asia. By examining both maternal and paternal haplogroups within the Iranian context, we aim to contribute to the broader narrative of human dispersals and elucidate the role those specific regions, such as the Iranian plateau, played in shaping the observed genetic diversity today. Due to the lack of comprehensive studies on mt-DNA /Y-DNA haplogroups in the Iranian population, our study sought to uncover the distribution of haplogroups among Iranian peoples using a large sample size. Our analysis focused on the frequency of ancestral haplogroups in Iran through the examination of large-scale whole-exome sequencing (WES) and SNP microarray data from 18,184 individuals. In our study, we observed 24 mt-DNA super haplogroups in the Iranian population, with the most common haplogroups belonging to West-Eurasian lineages U (20.73%), H (18.84%), J (12.10%), HV (9.22%), and T (8.98%), collectively comprising 69.70% of all Iranian samples. Notably, subclades J1 and U7 emerged as the two most frequent subclades, with frequencies of 11.24% and 7.30%, respectively. We also revealed the presence of 14 distinct Y-DNA haplogroups, with J, R, G, T, and Q emerging as the five predominant lineages. Notably, J2 (including J-L26) exhibited the highest frequency at 35.64%, followed by R1a at 14.68%. also, The detected mtDNA and Y-chromosome haplogroups were clustered into distinct groups that confirmed the heterogenicity of the Iranian population because of various factors including geographic or linguistic ethnic groups.