A recent genetic study has uncovered a high inbreeding rate of nearly 60% among South Indian communities, shedding light on the health implications of endogamy—the practice of marrying within a small group. Published in the Journal of Genetics and Genomics, the research highlights how this tradition, deeply tied to the caste system, increases the risk of passing down disease-causing gene variants, potentially leading to genetic disorders.

Led by Kumarasamy Thangaraj from the CSIR-Centre for Cellular and Molecular Biology in Hyderabad, the study analyzed blood samples from 281 individuals across four South Indian populations: Yadav (Puducherry), Kalinga and Reddy (Andhra Pradesh), and Kallar (Tamil Nadu). Using whole exome sequencing and data from the 1000 Genomes Project, the team found a 59% inbreeding rate across these groups. Thangaraj noted that endogamy is a key driver of population-specific diseases in India, yet comprehensive studies on its health impacts remain scarce.

The research also identified a high prevalence of ankylosing spondylitis, an inflammatory arthritis, among the Reddy population in Andhra Pradesh. This was linked to the genetic variant HLA-B27:04 and a "founder effect," where a small group establishes a population with limited genetic diversity. Additionally, the study uncovered population-specific gene variants tied to diseases and drug responses, offering insights for personalized medicine.

Co-author Dr. Sarath Chandra Mouli Veeravalli, a rheumatologist at Krishna Institute of Medical Sciences, emphasized the elevated incidence of ankylosing spondylitis in the Reddy community. Thangaraj stressed the need for genetic screening, counseling, and clinical care to address the health risks faced by such vulnerable groups. The findings underscore the broader implications of endogamy in India, calling for increased awareness and targeted healthcare interventions to mitigate genetic disease risks in these populations.