Immunoglobulin allotypes and estimation of genetic admixture among populations of Kinnaur District, Himachal Pradesh, India.

Four regional populations of the Kanet (Puh, Kalpa, Sangla, and Nachar) and an endogamous group of Koli from Kinnaur District, Himachal Pradesh, India, were studied to determine the extent of genetic variation of immunoglobulin allotypes (GM, KM, and AM) and the genetic contribution from ancestral populations of Tibet and northwest India. Haplotype GM*A G showed a higher frequency in the Kanet (40-60%)-a frequency that is more comparable to Asian populations-whereas in the Koli a lower frequency was observed, which is nearer the values for populations from northwest India. The IG haplotype data suggest that the Kanet population of Kinnaur District and the northeastern population of Nepal have different European origins than the more central population of India, represented by a sample from Delhi. The present results suggest that the populations of Kinnaur District are of admixed origin with contributions of Tibetan genes of 87.3%, 51.3%, 49.9%, 40.0%, and 9.5% in the Puh, Kalpa, Sangla, and Nachar Kanet and the Koli, respectively. The genetic distance obtained from 19 loci (9 blood groups, 8 biochemical markers, GM, and KM) showed an inverse relationship between the distance of the hybrid population from the parental gene pool. The Puh Kanet, nearest the Tibetan border, had the highest proportion of Tibetan genes but showed the lowest genetic distance with Tibetans. As the geographic distance of the other regional populations of the Kanet increases from the border of Tibet, genetic distance compared with the parental Tibetan population increases and the proportion of Tibetan admixture decreases. In the Kinnaur District admixture seems to contribute largely to the present-day observed high level of genetic differentiation.