Objective: The present investigation reports the genetic variation observed at two tetrameric short tandem repeat (STR) loci on chromosome 12 (D12S66 an d D12S67) among five anthropologically distinct population groups of India.

Subjects and methods: A total of 277 random normal and healthy volunteers were investigate d for the D12S66 locus, and 23 6 for the locus D12S67, from five ethnic groups of India. Two of these belong to the stat e of Maharashtra in western India (Konkanastha Brahmins and Marathas) and three fro m the stat e of Kerala in South India (Nairs, Ezhavas and Muslims). DNA was extracted from peripheral blood samples, amplifed by duplex polymerase chain reaction (PCR) and electrophoresed on 6% denaturing urea (7 M) gel electrophoresis. The analysis was performed on ALF Express DNA sequence r (Amersham Pharmacia Biotech) using Fragment Manager software. Statistical analysis was done by using Arlequinver. 1.1.

Results: At D12S66 locus, a total of nine alleles (8±17 repeats) and 27 genotypes were detected wit h an observed heterozygosity ranging from 0.55 to 0.91. At the D12S67 locus, nine alleles (36±44 repeats) an d 33 genotypes were observed with a heterozygosity ranging from 0.7 4 to 0.89. Both the loci displayed high Power of Discrimination (PD) which ranged from 0.81 to 0.9 1 and Polymorphic Information Content (PIC) ranging from 0.68 to 0.84. At D12S66, two alleles were detected for the first time in these population groups which were not reported earlier. The level of gene dierentiation (GSTvalue, 0.02) as moderate at these two loci, indicating a close relationship among the population groups.

Conclusions: From this investigation, it is concluded that both the tetrameric loci are highly polymorphic and informative, an d ca n be used for the characterization of the India n population groups in addition to other well-studied STR loci.