Ancestry Specific variation in neuropsychological disorders among the South Asian population

Abstract

The enormous genetic diversity in South Asia resulting from a long and complex admixture history resulted in the emergence of variation in various traits and variations in disease susceptibility. Neuropsychological disorders are one such example that shows variation at the population level. In this study, we aimed at understanding the variation in neuropsychological disorders at the population level among South Asian populations by curating, comparing and contrasting single nucleotide polymorphisms (SNPs), known to be associated with the same. Whole-genome data comprising of 1662 South Asians, belonging to 241 distinct populations were obtained from the database of Dr. David Reich, Harvard Medical School, USA. Principal Component Analysis (PCA) revealed that the Ancestral Tibeto Burman (ATB) genomes form a distinct and distinguishable cluster for the SNPs known to be associated with neuropsychological disorders. Identical By Descent (IBD) analysis showed that out of the top seven populations in terms of IBD sharing, six are from Southern India indicating that these populations may have undergone a recent selective sweep for these SNPs. Further, out of the top ten genomes, according to the number of genomes fixed for the minor alleles, seven were from Southern India. Furthermore, several indigenous populations from South India depicted high F values (>0.25) for SNPs associated with neuropsychological disorders, indicating higher susceptibility for neuropsychological disorders among these South Indian populations. Interestingly, we found that most of the SNPs, fixed for the alternative alleles, were also found to be fixed among the ancient genomes from Indus Valley Civilization (IVC), indicating that these SNPs likely got transmitted to various modern-day South Indian populations from IVC.