Multiple questions relating to contributions of cultural and demographical factors in the process of human geographical dispersal remain largely unanswered. India, a land of early human settlement and the resulting diversity is a good place to look for some of the answers. In this study, we explored the genetic structure of India using a diverse panel of 78 males genotyped using the GenoChip. Their genome-wide single-nucleotide polymorphism (SNP) diversity was examined in the context of various covariates that influence Indian gene pool. Admixture analysis of genome-wide SNP data showed high proportion of the Southwest Asian component in all of the Indian samples. Hierarchical clustering based on admixture proportions revealed seven distinct clusters correlating to geographical and linguistic affiliations. Convex hull overlay of Y-chromosomal haplogroups on the genome-wide SNP principal component analysis brought out distinct non-overlapping polygons of F*-M89, H*-M69, L1-M27, O2a-M95 and O3a3c1-M117, suggesting a male-mediated migration and expansion of the Indian gene pool. Lack of similar correlation with mitochondrial DNA clades indicated a shared genetic ancestry of females. We suggest that ancient male-mediated migratory events and settlement in various regional niches led to the present day scenario and peopling of India.

Human plasma chitotriosidase activity is a commonly used diagnostic and therapeutic biomarker for non-neuronopathic Gaucher disease. Chitotriosidase deficiency is common in non-African populations and is primarily caused by a 24 bp duplication in the encoding gene (CHIT1). Allele frequencies for the 24 bp duplication range from 20-50 % outside

Epidemiological evidence suggests that an adverse in utero environment is associated with an increased risk for developing adult onset diseases. The molecular mechanisms for susceptibility to chronic noncommunicable diseases are not fully understood, although recent research has proposed that epigenetic modifications play an important role in fetal programming. Genetic and environmental factors contribute to interindividual and spatiotemporal tissue-specific methylation patterns. Although the diverse environments and high genetic diversity of African populations provide unparalleled potential to investigate the effects of environmental change on the epigenetic profile in humans, only a small percentage of genomic and epigenetic studies have focused on populations from this continent. This emphasizes the need to build capacity in Africa for research that leads to an understanding of the association between genetic, epigenetic and environmental risk factors for noncommunicable diseases on the continent.

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