Genetic researchers probe nuclear genome to explain exceptionally high TB burden among MPs Sahariyas
BHOPAL: Genetic science researchers from across the country have turned their focus to genomic factors that may underlie the abnormally high prevalence of tuberculosis (TB) among the Sahariyas, one of the three Particularly Vulnerable Tribal Groups (PVTGs) in Madhya Pradesh. The Sahariya population is largely concentrated in the GwaliorChambal region of Madhya Pradesh, particularly in Sheopur, Shivpuri, Guna, Ashoknagar, Gwalior, Morena and Bhind districts, with some presence in adjoining parts of Bundelkhand. Reported TB prevalence among the community ranges between 1,518 and 3,294 cases per 100,000 population, at least eight times higher than the national average of 187 per lakh. According to the World Health Organizations Global TB Report 2025 , India, despite remaining among high-burden countries, has recorded a 21 per cent decline in new TB cases, from 237 per lakh population in 2015 to 187 per lakh in 2024. Against this backdrop, the Sahariyas stand out as an extreme outlier. The ongoing research is being led by Prof Gyaneshwar Chaubey, a noted geneticist and biological anthropologist at Banaras Hindu University (BHU), Varanasi, in collaboration with researchers from several institutions, including the University of Calcutta and the Forensic Science Laboratory, Jabalpur. The team has already made a significant breakthrough by linking rare maternal mitochondrial haplogroups, N5 and X2, to heightened TB susceptibility among the Sahariyas. A haplogroup refers to a group of people who share a common ancestor, identified through specific mutations in mitochondrial DNA (inherited from the mother) or Y-chromosome DNA (inherited from the father). The findings, published in the international journal Mitochondrion in August 2025, were based on the analysis of complete mitochondrial genomes from 729 individuals, including 140 Sahariyas. The study revealed that the rare N5 and X2 haplogroups, absent in neighbouring populations, likely entered the Sahariya gene pool through ancient gene flow from western India during the early Iron Age. A subsequent founder effect may have compromised mitochondrial function, weakening immune responses to TB. Researchers noted that this genetic vulnerability, compounded by chronic malnutrition, poverty and limited access to healthcare, offers a compelling explanation for the tribes extraordinarily high TB burden. Building on these mitochondrial findings, the research team has now initiated whole-genome sequencing of Sahariya individuals to investigate the contribution of the nuclear genome to TB susceptibility. This phase aims to identify risk alleles or genetic variants in nuclear DNA that may act independently or in concert with mitochondrial factors to heighten disease vulnerability. The study is also examining long-standing patterns of endogamy within the community. High levels of marriage within the group, combined with a historically small effective population size, may have amplified harmful genetic variants through genetic drift and inbreeding. Preliminary analyses suggest that this demographic history could further intensify TB risk by concentrating deleterious alleles. Expanding from mitochondrial insights to nuclear genomics will give us a far more comprehensive understanding of genetic susceptibility among the Sahariyas, said Debasruti Das, the studys first author. This knowledge is crucial for designing targeted interventions for communities bearing the heaviest TB burden. Senior author Prof Prashant Suravajhala added that the ongoing work would also assess how genetic predisposition interacts with environmental and cultural factors. Such integrated insights can pave the way for personalised public health strategies and more effective TB control among tribal populations, he said.
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