Detection of genetic variation in Indian population groups using a novel minisatellite probe and finding relationships through tree construction

Genetic variation in HaeIII-digested genomic DNA samples from different ind ividuals belonging to population groups from Bengal, Uttar Pradesh (UP), Pu njab, and South India was assessed at hypervariable loci, using a minisatel lite probe. pBA1.2 (accession number, AF 157691), the repeat unit of which was 24 mer long and rich in G-bases. Comparison of DNA profiles between ind ividuals showed a very low probability of band sharing, which ranged from 0 .18 to 0.24. A dendrogram, based on Nei's genetic distance, constructed by the neighbor-joining method, showed the formation of separate clusters by b oth South Indian and non-Indian samples, whereas the construction of a dend rogram based on the Unweighted pair group method arithmetic average (UPGMA) method with Jaccard's similarity coefficient at the individual level led t o the formation of several small clusters which were interleaved; also, the subgroups for each of the populations were intermingled with the subgroups for the other populations. a separate analysis was carried out to check th e consistency of the proximity between different individuals forming a clus ter and between those individuals who were in the vicinity of two clusters. The dendrograms thus obtained did not change the relationship between the individuals from all the populations studied. Despite the distinct clusteri ng observed in the population group comparison, a probable admixture was re flected in the finding that some individuals belonging to one population gr oup were dispersed or embedded within a cluster generated by the individual s of another population group, when a minute dissection of the data for gen erating a tree at the individual level was carried out.