STR polymorphisms in Sri Lanka: evaluation of forensic utility in identification of individuals and parentage testing.

Objectives: This preliminary study was carried out to determine the allele frequencies and forensic efficiency parameters for the short tandem repeat loci CSF1PO, TPOX, THO1, D16S539, D7S820, D13S317, vWA, FESFPS and F13B in a test sample population of Sri Lankans.

Design: Test samples were obtained from 305 non-related individuals originating from all 9 provinces of Sri Lanka. DNA was extracted from whole blood using chelex-100 and amplified by PCR using the GenePrint STR kit and silver stained. Final DNA profiles were analysed for forensic efficiency parameters and paternity indices using PowerStats version 12. Possible divergence from Hardy-Weinberg Equilibrium was tested using the chi-square test and exact test.

Results: All common alleles in the allelic ladders were found in the test sample studied. PIC values >0.5 for all 9 STR loci indicate this STR system to be informative and useful for identification purposes. The D13S317, vWA and D7S820 loci were found to be the most polymorphic markers of the system studied.

Conclusions: No deviations from Hardy-Weinberg Equilibrium were found for any of the loci examined. The results indicate that the 9 STR loci system described here is suitable for estimating DNA profile frequencies in human identification and forensic and parentage testing for legal purposes among Sri Lankans.