Paternity testing using 21 STR Loci in a biotechnology approach: case of Rwandan Population

Abstract

INTRODUCTION: We focused on a sample size of 141 unrelated Rwandan persons to genotype
21 STR loci that were relied up in establishing allele frequencies, heterozygosity and power of
exclusion. This study aims at exploring allele frequencies on a representative sample from Rwandan
population to determine probability of paternity for sampled families basing on polymorphic STRs
loci, using 21 autosomal-STR loci by Genetic Analyzer 3500X.
METHODS: This was an experimental study and global filer TM Express PCR Amplification kit was
used to amplify 21 autosomal STR loci.
RESULTS: The total number of observed alleles was 270; the largest number of different alleles
was seen in SE33 and D18S51 loci. The locus with the highest heterozygosity was SE33, while locus
TH01 had the lowest heterozygosity. The heterozygosity of the 21 STR loci ranged from 71.3%
(TH01) to 91.6% (SE33) with an average of 81.1% a good indicator of high genetic variability. For
all microsatellites analyzed the power of exclusion ranged from 43.4% (TH01) to 78.1% (SE33)
with an average of 58.2%. For seven of eight cases examined in paternity test alleged father was
not excluded as biological father of child. The results found in examination of case 8 indicated that
the alleged father was not the biological father of the child.
CONCLUSION: Based on calculated statistical parameters, the population of Rwanda may use
these 21 STR loci as a vital tool for forensic identification and paternity testing.