Genetic data of 10 X-STRs in a population sample from Lima,Perú

Genetic population data for 10 X-STR (DXS6789, DXS9902, DXS7132, GATA31E08, DXS7133, DXS9898, DXS8378, DXS6809, DXS7423 and GATA172D05) were obtained from Lima population. The present study results support the usefulness of these markers in kinship investigation and also in population genetics studies.     

Characterization of NIST standard reference materials by next generation sequencing

The National Institute of Standards and Technology (NIST) offers certified Standard Reference Materials (SRMs) for laboratories which perform DNA-based human identity testing. Developed by the Applied Genetics Group at NIST, forensic DNA SRMs are well characterized for relevant markers such as autosomal and Y-chromosomal short tandem repeats (STRs) and mitochondrial DNA (mtDNA) sequence. Characterization of the SRMs has been performed by capillary gel electrophoresis fragment-based genotyping analysis and/or Sanger type sequencing. New technologies, commonly referred to as next generation sequencing (NGS), now offer an opportunity to validate the certified DNA-based reference materials using an orthogonal method and thereby increase the confidence in the certified values of the materials. The increased sensitivity of NGS will facilitate expansion of the information content of NIST SRMs through the characterization of new features which are beyond the ability of fragment-based analysis or Sanger sequencing to detect. This work will also lead to the availability of Certified Reference Materials for laboratories wishing to implement and validate NGS technology in the field of forensics.     

On the meaning of the likelihood ratio: Is a large number always an indication of strength of evidence?

There is general lack of awareness that high LR based on complex propositions e.g. three contributors, does not necessarily translate into probative evidence against a suspect. In some cases there is an increased chance of false inclusion of a person of interest. This is an issue for all LR-based models. One way to address this issue is to further evaluate or qualify the estimated LR by a performance test. Based on simulations, this was achieved by non-contributor-testing: replacing the reference profile of interest (typically the suspect's profile), by the profile of a simulated random man. An exact p-value can also be calculated, giving the chance of observing an LR-value exceeding the estimated if the defense hypothesis is true.     

Genetic profile of nine autosomal STR loci among Halakki and Kunabhi populations of Karnataka, India

POPULATION: Blood samples were collected from a total of 84 healthy and unrelated Halakki (44) and Kunabhi (40) populations, with their informed written consent. The geographic location of the sampled area is shown in Fig. 1. Both the populations are endogamous, and they belong to Dravidian linguistic family. Halakki is a tribal group having a population size of approximately 3383. They claim that they originally belong to Gujarat and Rajasthan, and migrated through Andhra Pradesh to Karnataka. Kunabhi is also a tribal population, who are approximately 35,214 in number. The male Kunabhi can be identified by their tattoo marks. A necklace is the symbol of married women. They were hunters and gatherers, but at present they practice agriculture.     

A proposal for standardization in forensic canine DNA typing: allele nomenclature of six canine-specific STR loci

In this study a proposal for the allele nomenclature of six polymorphic short tandem repeat (STR) loci (PEZ3, PEZ6, PEZ8, PEZ10, FHC2161, and FHC2328) for canine genotyping (Canis lupus familiaris) is presented. The nomenclature is based on the sequence data of the polymorphic region of the microsatellite markers as recommended by the DNA commission of the International Society of Forensic Haemogenetics (ISFH) in 1994 for human DNA typing. To cover commonly and rarely occurring alleles, a selection of homozygous and heterozygous animals were analyzed and subjected to sequence studies. The alleles consisted of simple tri- and tetra-nucleotide repeat patterns as well as compound and highly complex repeat patterns. Several alleles revealing the same fragment size but different repeat structures were found. The allele designation described here was adopted to the number of repeats, including all variable regions within the amplified fragment. In a second step the most commonly occurring alleles were added to an allelic ladder for each marker allowing a reliable typing of all alleles differing in size. A total number of 142 unrelated dogs from surrounding municipal animal homes, private households, and canines in police duty were analyzed. The data were added to a population database providing allele frequencies for each marker.     

The application of miniplex primer sets in the analysis of degraded DNA from human skeletal remains

A new set of multiplexed PCR primers has been applied to the analysis of human skeletal remains to determine their efficacy in analyzing degraded DNA. These primer sets, known as Miniplexes, produce shorter amplicons (50-280 base pairs (bp)) than standard short tandem repeat (STR) kits, but still utilize the 13 CODIS STR loci, providing results that are searchable on national DNA databases. In this study, a set of 31 different human remains were exposed to a variety of environmental conditions, extracted, and amplified with commercial and Miniplex DNA typing kits. The amplification efficiency of the Miniplex sets was then compared with the Promega PowerPlex 16 system. Sixty-four percent of the samples generated full profiles when amplified with the Miniplexes, while only 16% of the samples generated full profiles with the Powerplex 16 kit. Complete profiles were obtained for 11 of the 12 Miniplex loci with amplicon sizes less than 200 bp. These data suggest smaller PCR amplicons may provide a useful alternative to mitochondrial DNA for anthropological and forensic analysis of degraded DNA from human skeletal remains.     

Population data for four population groups from the United States for the eleven Y-chromosome STR loci recommended by SWGDAM

POPULATIONS: Caucasian ( n =1243), African American ( n =1605), Hispanic ( n =454), and Native American ( n =104).     

Genetic polymorphisms at four STR loci from the HLA region in a Venezuelan population

POPULATIONS: Whole blood samples from 74 unrelated healthy individuals were collected. The donors' sample included Venezuelan mestizos from various regions of the country, but mostly from the resident population of Caracas City. A Venezuelan mestizo is the offspring of a mating between a native Venezuelan and a person born in Europe, mainly in Spain.     

Laser microdissection separation of pure spermatozoa from epithelial cells for short tandem repeat analysis

Short tandem repeat (STR) analysis is a valuable tool in identifying the source of biological stains, particularly from the investigation of sexual assault crimes. Difficulties in analysis arise primarily in the interpretation of mixed genotypes when cell separation of the sexual assailant's sperm from the victim's cells is incomplete. The forensic community continues to seek improvements in cell separation methods from mixtures for DNA typing. The feasibility of applying laser microdissection (LMD) technology to precisely separate sexual assault cell mixtures by visual inspection coupled with laser dissection was assessed through three experiments. First, various histological stains were evaluated for use with LMD and DNA analysis. Second, different DNA isolation methods were evaluated on LMD-collected cells. Finally, STR analysis was performed on LMD-separated sperm cells from mixtures of semen and female buccal epithelial cells. The results indicated (a) hematoxylin/eosin staining performed best in its ability to differentiate sperm and epithelial cells while exhibiting the least negative effect on further downstream analysis; (b) both QIAamp and Lyse-N-Go methods were useful for recovery of DNA from LMD-collected sperm cells; and (c) LMD separation provided clear STR profiles of the male donor with the absence of any additional alleles from the female donor. This report describes an efficient, low-manipulation LMD method for the efficient separation of spermatozoa from two-donor sperm/epithelial cell mixtures.