Genetic Heterogeneity and Gene Diversity at ABO and Rh Blood Group Polymorphisms in Seven Pashtun Populations of Upper Khyber Pakhtunkhwa, Pakistan

Pashtun population in the North-West Pakistan is ethnically, culturally and compositionally very distinct from the rest of Pakistanis. Pashtuns are important for the understanding of genetic affinities of Pakistanis with other populations like Afghans, Central Asians and Aryans. To get an overview of their genetic structure, we have assembled the ABO and Rh blood group polymorphisms data of 83,000 subjects from seven Pashtun populations of upper Khyber Pakhtunkhwa, namely Buner, Mardan, Dir-Lower, Swabi, Swat, Nowshera, and Peshawar. We establish that these populations despite their linguistic and ethnic affinities, exhibit ample variation at the blood group markers. The frequencies of alleles p(A), q(B) and r(O) ranged from 18.7—23.2%, 22.0—26.5%, and 53.9—57.7%, respectively, while allele Rh(d) remained 21.5—31.4%. The average heterozygosities ranged from 0.458 to 0.517 in Swabi and Swat populations, respectively. Comparison of genotypic frequencies, homogeneity tests for allelic frequencies, and heterozygosity analyses reveal that a straightforward clustering of these populations was not possible. Furthermore, gene diversity analyses yielded total heterozygosity, HT =0.4901, and DST =0.0012, while coefficient of gene differentiation, GST was calculated to be 0.0024. Nei's measure of genetic distance (DA) was found to be highest between Swabi and Swat samples, and lowest between Dir-Lower and Mardan. These results established substantial differentiation and substructuring among these populations. Further investigations by employing highly polymorphic molecular markers would be indispensable in getting a deeper insight into the genetic diversity of Pashtuns and identifying the underlying evolutionary force causing this differentiation.