Allele Frequencies For 20 Autosomal Microsatellite Loci In The Kenyan Population

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 and0.831 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 from0.69 to 0.90 with Penta E returning the highest score. The high PIC score shows that the additional markers offer amore informative value of the genetic markers in this data set. The power of discrimination ranged from 89% to97% 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.

“Just Bring Us the Real Ones”: The Role of Forensic Crime Laboratories in Guarding the Gateway to Justice for Sexual Assault Victims

Throughout the United States, hundreds of thousands of sexual assault kits (SAKs; also termed “rape kits”) have never been submitted by law enforcement personnel to a crime laboratory for forensic DNA testing. Prior research indicates that negative stereotypes about victims influence police decisions to submit kits for testing, but forensic crime laboratory personnel may also be involved in SAK submission decisions. The purpose of the current study was to explore the communication and collaboration between police and crime lab personnel regarding SAK submissions within a community with large numbers of unsubmitted rape kits. Drawing from 3 years of ethnographic observations and longitudinal qualitative interviews, we found that the police department’s crime lab did not have sufficient resources to test all rape kits in police custody, which is a problem forensic laboratories are facing throughout the United States. However, we also found that access to this limited resource was controlled by crime lab personnel and their rape myth beliefs about which victims and which cases were considered worthy of the time, effort, and attention of the criminal justice system. Lab personnel emphasized that police should only submit “real” cases for forensic DNA testing, which they typically defined as physically violent stranger-perpetrated sexual assaults; “shady” cases did not merit testing, which they defined as known-offender assaults, reports made by adolescent victims, and cases in which the victim may have been engaged in sex work. We noted marked similarities in police and lab personnel’s rape myth acceptance, and stakeholders readily agreed that they did have a common understanding about which victims were not credible and therefore which SAKs did not merit testing. We discuss these findings in light of recommendations from the National Academy of Sciences for the independence and autonomy of the forensic sciences from law enforcement.

Crime Scene Analysis Through DNA Testing of Canine Feces—A Case Report

Forensic DNA testing can play a critical role in homicide investigations. Selecting the appropriate evidence on which to perform DNA testing requires foresight and reasoning based on experience and science. Although successful DNA testing can occur using many substrates, including blood, hair, and sweat/epithelial cells, positive results can also result from testing various unorthodox samples. The authors report on a triple-murder investigation where DNA testing of dog feces at the crime scene matched DNA testing of feces found on the shoe of a suspect resulting in successful prosecution of the case.