title: Genetic variation observed at two tetrameric short tandem repeat loci on chromosome 12 (D12S66 and D12S67) among five distinct ethnic groups of India: detection of two new alleles.
abstract: OBJECTIVE
  The present investigation reports the genetic variation observed at two tetrameric short tandem repeat (STR) loci on chromosome 12 (D12S66 and D12S67) among five anthropologically distinct population groups of India.
  
  
  METHODS
  A total of 277 random, normal and healthy volunteers were investigated for the D12S66 locus, and 236 for the locus D12S67, from five ethnic groups of India. Two of these belong to the state of Maharashtra in western India (Konkanastha Brahmins and Marathas) and three from the state of Kerala in South India (Nairs, Ezhavas and Muslims). DNA was extracted from peripheral blood samples, amplified by duplex polymerase chain reaction (PCR) and electrophoresed on 6% denaturing urea (7 M) gel electrophoresis. The analysis was performed on ALF Express DNA sequencer (Amersham Pharmacia Biotech) using Fragment Manager software. Statistical analysis was done by using Arlequin ver. 1.1.
  
  
  RESULTS
  At D12S66 locus, a total of nine alleles (8-17 repeats) and 27 genotypes were detected with an observed heterozygosity ranging from 0.55 to 0.91. At the D12S67 locus, nine alleles (36-44 repeats) and 33 genotypes were observed with a heterozygosity ranging from 0.74 to 0.89. Both the loci displayed high Power of Discrimination (PD) which ranged from 0.81 to 0.91 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 differentiation (G(ST) value, 0.02) was 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, and can be used for the characterization of the Indian population groups in addition to other well-studied STR loci.
authors.affiliation: Low Level Radiation Research Laboratory, Cell Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.
authors.forename: Birajalaxmi
authors.initials: B
authors.lastname: Das
authors.forename: P S
authors.initials: PS
authors.lastname: Chauhan
authors.forename: M
authors.initials: M
authors.lastname: Seshadri
mesh_terms: D000483:Alleles; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics*; D005006:Ethnicity / Q000235:genetics; D005787:Gene Frequency; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D007194:India; D018895:Microsatellite Repeats