Genetic heterogeneity and population structure in north-west India.

Genetic markers consisting of 11 blood group and red cell enzyme systems were investigated in 14 endogamous groups of north-west India. Genetic differentiation among the samples as indicated by FST is appreciable, reflecting the ethnic diversity characteristic of this region. Local variation within each state is lower, indicating a geographical component to the total variation. This variation is refined by calculations of genetic distances, which show that the tribals and low-caste groups are closer together but well separated from high-caste Brahmins and other non-tribal middle castes. There is a slight possibility of disruptive selection, but the analyses suggest that the differences in genetic structure in north-west India are more likely to be due to their breeding structure, differential migration and ethnic affiliation.