Allele frequencies of 20 Y-chromosomal short tandem repeat loci in a tribal population of Deccan Plateau, India

Population: Eighty male individuals from a nomadic tribal population belonging to Dravidian and Indo-Caucasian ethnicities from Deccan Plateau, Andhra Pradesh, India, were analyzed in the present study.     

Expedited, chemically enhanced sperm cell recovery from cotton swabs for rape kit analysis

This report focuses on the development of a method for chemically induced enhancement of cell elution and recovery from cotton swabs. The method exploits the exclusive use of detergents for intact cell removal, and can be utilized in conjunction with, or to circumvent, conventional differential extraction (DE). Samples treated with Sarkosyl (54.4 +/- 1.8%) and sodium dodecyl sulfate (SDS) (78.5 +/- 0.7%) yielded higher sperm cell recoveries than a conventional DE buffer (39.4 +/- 2.1%). The results indicated that the choice of detergent affected sperm cell yield, with anionic detergents having the greatest effect. Storage time of samples affected the concentration of detergent required for optimal sperm cell recovery, longer times requiring increased detergent concentrations. In addition, the extent of sperm cell lysis by proteinase K digestion was evaluated. The results indicate that the exclusive use of SDS enhances the release of sperm and epithelial cells from a cotton swab as compared with DE buffer, providing for a more effective DNA analysis.     

Y-chromosomal STR haplotypes in two endogamous tribal populations of Karnataka, India

POPULATION: Approximately 5.0 mL of blood sample was collected from a total of 150 men belonging to two tribal populations of coastal Uttar Kannada district of Karnataka, with their informed written consent. Both the populations are endogamous and they belong to the Dravidian linguistic family. Halakki is a tribal group having a population size of c. 3383. They claim that they originally belong to Gujarat and Rajasthan, and migrated through Andhra Pradesh to Karnataka. Kunabhi is also a tribal population, c. 35,214 in number. They were hunters and gatherers but presently they practice agriculture.     

Concordance study between the AmpFlSTR MiniFiler PCR amplification kit and conventional STR typing kits

The AmpFlSTR MiniFiler polymerase chain reaction amplification kit developed by Applied Biosystems enables size reduction on eight of the larger STR loci amplified in the Identifiler kit, which will aid recovery of information from highly degraded DNA samples. The MiniFiler Kit amplifies CSF1PO, FGA, D2S1338, D7S820, D13S317, D16S539, D18S51, and D21S11 as well as the sex-typing locus amelogenin. A total of 1308 samples were evaluated with both the MiniFiler and Identifiler STR kits: 449 African American, 445 Caucasian, 207 Hispanic, and 207 Asian individuals. Full concordance between Identifiler and MiniFiler Kits was observed in 99.7% (10,437 out of 10,464) STR allele calls compared. The 27 differences seen are listed in Table 1 and encompass the loci D13S317 (n = 14) and D16S539 (n = 10) as well as D18S51 (n = 1), D7S820 (n = 1), and CSF1PO (n = 1). Genotyping discrepancies between the Identifiler and MiniFiler kits were confirmed by reamplification of the samples and further testing using the PowerPlex 16 kit in many cases. DNA sequence analysis was also performed in order to understand the nature of the genetic variations causing the allele dropout or apparent repeat unit shift.     

Developmental validation of reduced-size STR Miniplex primer sets

This paper describes a developmental validation study of three Miniplex sets covering 12 of the 13 CODIS loci. As these new sets will be used for the analysis of degraded and low level DNA, the validation studies were performed using 100-125 pg of DNA, the lowest input level at which peak balance, peak intensity, and allele consistency were stable. To demonstrate the applicability of the Miniplex sets to forensic casework, these validation studies were completed in accordance with the Scientific Working Group on DNA Analysis Methods (SWGDAM). A range of tests were performed including studies of concordance with standard multiplex kits, sensitivity and reproducibility, and PCR amplification conditions. Additionally, studies of mixtures, nonhuman and environmentally degraded DNA, and simulated forensic samples were performed. Our results demonstrate that Miniplex STR amplification procedures are a robust and sensitive tool for the analysis of degraded DNA.     

Genetic data of 4 X-chromosomal short tandem repeats in a North of Portugal population

POPULATION: One hundred unrelated females and 100 unrelated males, autochthonous, healthy, from the North of Portugal.     

Comparison of two whole genome amplification methods for STR genotyping of LCN and degraded DNA samples

The analysis of LCN or highly degraded DNA samples presents a challenge for forensic science. Improving the quantity and/or quality of samples would greatly increase the profiling success rate from LCN and degraded samples. Whole genome amplification (WGA) is one method that has such potential. Two commercially available WGA kits, GenomePlex and GenomiPhi, were investigated for use on LCN and degraded DNA samples. Both kits amplified genomic DNA, producing microgram quantities from sub-nanogram templates. Profiling success of LCN DNA samples was increased, with improvements of over 700% from 10pg template DNA compared to non-WGA-amplified control samples. The amplification success with degraded DNA was also improved by WGA. Degraded DNA was simulated using restriction enzymes to demonstrate that the application of WGA can result in the typing of STR loci that could not previously be amplified. An increase in artefacts, such as stutter alleles and amplification biases, were observed in many samples. Results show that WGA is capable of increasing both the quality and quantity of DNA, and has the potential to improve profiling success from difficult samples in forensic casework.