Population data on short tandem repeat loci for person identification and paternity test

Abstract

Short tandem repeat (STR) loci are highly polymorphic markers composed of short, repetitive sequence elements of 1 to 6 base pairs in length and display Mendelian inheritance characteristics. STR loci are amenable to analysis by polymerase chain reaction. STR has become a powerful technique in forensic DNA typing. Prior to introduction of a new DNA profiling method, a statistical analysis of the population needs to be undertaken. The aim of this study was to establishe population data of STR loci in the Thai population. Whole blood samples of 200 unrelated individuals were collected. DNA was extracted by the salting-out method and quantitated by measuring the optical density at 260 nm. The tetrameric STR loci for amplification were CSF1PO, TPOX, TH01, F13A01, FESFPS, F13B, LPL and vWA. The PCR products were separated by denaturing polyacrylamide gel electrophoresis and detected by silver staining. A total of 10 alleles for F13A01 and vWA, 8 alleles for CSF1 PO, 7 alleles for FESFPS, 6 alleles for TH01 and LPL, and 5 alleles for TPOX and F13B can be observed. The range of observed heterozygosity is between 42% and 86%. No significant deviation from the Hardy-Weinberg equilibrium (p >.05) between observed and expected genotype frequencies has been found in any one system. Three of the eight loci examined (F13B, LPL and TPOX) do not appear as highly polymorphic as observed in other populations. For the other six loci, the combined average power of exclusion (PE) is 0.9834and the combined discrimination power (DP) is 0.999995. Hence, the combination of these useful systems results in a more powerful DNA typing and can be used as a battery for person identification and paternity test.