Allele Frequencies For 20 Autosomal Microsatellite Loci In The Kenyan Population

Abstract

Samples from 180 unrelated persons of Kenyan descent collected at a DNA testing facility in Nairobi were genotyped using the PowerPlex21® STR kit to generate the first indigenous 20 autosomal STR allele frequency table for use in forensic analysis of human DNA in Kenya. Informed consent for use of the samples for this study was obtained with de-identification procedures employed in accordance with recommendations from the Scientific and Ethics Review Unit at the Kenya Medical Research Institute (KEMRI). The markers amplified for the generation of the allele frequency table were D3S1358, D13S317, PentaE, D16S539, D18S51, D2S1338, CSF1PO, Penta D, THO1, vWA, D21S11, D7S820, TPOX, D8S1179, FGA, D2S1338, D5S818, D6S1043, D12S391, and D19S433. A high degree of gene diversity was observed in this population with average PIC values and heterozygosity of 0.799 and 0.831 respectively across the 20 loci. Cumulatively, 182 alleles were detected in the Kenyan population analysed across the 20 STR loci. The lowest allele frequency value was 0.003 where one occurrence of the allele was observed while the highest allele frequency was 0.36 for allele 16 marker D3S1358. Polymorphism information content (PIC) results ranged from 0.69 to 0.90 with Penta E returning the highest score. The high PIC score shows that the additional markers offer a more informative value of the genetic markers in this data set. The power of discrimination ranged from 89% to 97% with a combined power of discrimination of 99.99%. The combined match probability, a measure in population genetics that is used to measure the chance of an unrelated person, arbitrarily picked out of the common population and having an identical genotype as that derived from the reference sample or the evidence, was 4.34 x 10-26. The dataset generated in the present study has been demonstrated to be highly valuable in discriminating between two individual genotypes and greatly amplifies the power of discrimination available to Kenyan forensic DNA testing facilities. The loci included in this dataset comprise the commonly used loci in the US, Europe and Asia and the development of this allele frequency table increases the data sharing possibilities between local and international forensic DNA testing facilities. Key words: Autosomal STR, variation, Kenyan, statistical parameters, Allele frequency. …