The rural urban divide, insights from immuno-genetic profiles and implications for health

Abstract

Population disparities in health and disease, has been observed, and amply documented. While often attributable to genetic underpinnings, such disparities, extends beyond population genetic predisposition to include environmental and geographic determinants most pronouncedly the division between rural and urban lifestyles. Under such influences, genes and gene products may become affected by epigenetic factors, microbial modifiers including infections and the body microbiome that ultimately shapes the outcome of complex milieu of protein networks. Retrospective, demographic, genotype, and expression data of two rural populations from eastern Sudan were analysed for genotype, allele frequency distribution, Hardy Weinberg Equilibrium and expression profiles using an array panel of Th1, Th2 and Th3 genes in a subset of rural population sample against matched urban control. Differences between urban and rural samples were observed in the departure from HWE with excess of heterozygosity in the rural sample. In the Th1, Th2 and Th3 array, cytokines were consistently overexpressed in the rural as compared to urban cohort and was replicated in 7 selected genes that are associated with chronic diseases amongst urban dwellers in contrast to rural village inhabitants. IgE levels as feature of parasitic infections is one other difference to include in that dichotomy. Gene expression appears to be more exposing to an overall outcome of genetic variations, including the interaction with environmental influences within and outside the body. Here, it may be gathered from the contrast in the expression patterns between the rural and urban samples. The presence of signals of natural selection in genes that are key to certain biological functions as CD40L and FasL, and the sharp contrast between urban and rural populations in gene variants distribution and expression patterns may provide important clues towards understanding the disparity between human communities in non-communicable diseases of lifestyle as well as some of the emerging infectious diseases.