Population genetic analysis of five northwest Punjabi endogamous groups using microsatellite markers

Previous episodes of foreign migration and invasion led to massive gene flow into the population of Punjab, especially, Northwest Punjab, as invaders came through this route. Furthermore, regional conversions from different castes occurred during the period of Islamic dominance. The present study is motivated by the fact that negligible study is available regarding genetic structure of Punjabi population. In purview of this the present study was conducted to analyze the genetic structure, relationship and gene flow in five endogamous population groups, namely Jat Sikh, Mazhbi Sikh, Brahmin, Ramdasia and Muslim, from the Northwest districts of Punjab, based on microsatellite loci. A total of 751 subjects, including 154 Jat Sikh, 148 Mazhbi Sikh, 151 Brahmin, 148 Ramdasia and 150 Muslim samples were analyzed for six autosomal microsatellite markers (THO1, TPOX, CSF1PO, vWA, D7S820 and FGA). Statistical analyses were performed to interpret allele frequencies, heterozygosities, gene diversity, analysis of molecular variance (AMOVA), phylogenetic analysis (neighbor joining (NJ) method) and multidimensional scaling (MDS). The average heterozygosity for each locus in each population as a whole was substantial. Significant deviations from HWE were observed in almost all the populations and all the loci. In the entire analyses the Brahmin and the Mazhbi Sikh formed same cluster, while Jat Sikh and Ramdasia were placed close to their cluster, whereas, Muslim population group maintained the genetic distance from all the other population groups. Jat Sikh, Mazhbi Sikh, Brahmin and Ramdasia groups formed a clear and distinct separate cluster when compared with other Indian populations. The present study has also examined the affinities of Northwest Punjabi population with international populations, and some elements of central Asia, Middle East, Caucasoid and European populations were evident among the present studied groups. In conclusion, overall, a low level of genetic differentiation was observed in the studied population groups, especially, Jat Sikh, Mazhbi Sikh, Brahmin and Ramdasia indicating that genetic drift might have been small or negligible in shaping the genetic structure of the Northwest Punjabi populations.