Sequence variation of the Mitochondrial DNA hypervariable segment II in some ethnoreligious groups in Iraqi Kurdistan

Mitochondrial DNA is widely used in population genetics to trace maternal lineage due to its high mutation rate, lack of recombination and exclusive maternal inheritance. This study examines variation in the hypervariable region II (HVS II) of mtDNA among three ethnoreligious groups living in Iraqi Kurdistan.

A total of 90 samples were included in this study: 34 Bahdini Kurds, 30 Shabaks, and 26 Chaldeans. The HVS-II region was amplified and sequenced for all samples. Sequences were aligned with the revised Cambridge Reference Sequence (rCRS), and detected polymorphisms included nucleotide substitutions, insertions, and deletions.

Several high-frequency polymorphisms were detected across all ethnoreligious groups, such as A263G and 315.1 C. Haplotype diversity was high in all three groups, with values above 0.93, indicating a high maternal genetic variation. The neutrality tests for all the ethnoreligious groups yielded non-significant negative Tajima's D values, which may be an indicative of demographic expansions. The results indicate low genetic differentiation of maternal lineage among the studied ethnoreligious groups at the HVS-II level. Pairwise ΦST values and analysis of molecular variance (AMOVA), showed that most of the genetic variation occurred within the groups rather than between them.

The findings suggest limited genetic differentiation among the studied ethnoreligious groups in Iraqi Kurdistan. These findings highlight the importance of this region as a historical crossroad for human populations and contribute to reconstructing the genetic history of the Near East.