Distribution of HLA-DQA1, polymarker, CSF1PO, vWA, TH01, TPOX, D16S539, D7S820, D13S317, and D5S818 alleles in East Bengali and West Punjabi populations from Indo-Pak Subcontinent

Blood samples were collected from 115 individuals residing in the Pakistani state of West Punjab and 81 Bengali individuals residing in the state of East Bengal, India. These samples were analyzed for the loci HLA-DQA1, PM (LDLR, GYPA, HBGG, D7S8, and GC) and eight short tandem repeats: CSF1PO, TPOX, THO1, vWA, D16S539, D7S820, D13S317, and D5S818. Departures from Hardy-Weinberg (HWE) were observed in Punjabi population at LDLR, THO1, D13S317, D5S818, and D16S539 and at CSF1PO and THO1 in Bengali population.     

The presumptive reagent fluorescein for detection of dilute bloodstains and subsequent STR typing of recovered DNA

A presumptive reagent for dilute blood detection other than luminol is fluorescein. The sensitivity of fluorescein approaches the sensitivity of detection levels of luminol. The fluorescein detection method offers the advantages of working in a lighted environment, and the reaction persists longer than luminol. A series of diluted bloodstains, ranging from neat to 1:1,000,000, was placed on a variety of substrates. Three sets were made per substrate. One set was exposed to fluorescein, one set was exposed to luminol, and one set served as an uncontaminated control. The fluorescein signal persisted longer than luminol. However, background staining for fluorescein was observed on some substrates within 30 s to 1 min, and no background staining was observed for luminol. Stains on non-absorbent surfaces were detectable at 1:100,000 dilutions, and stains on absorbent surfaces were detectable usually at no more than 1:100. The sensitivity of detection of fluorescein was comparable to that of luminol in this study. In all cases, where sufficient DNA was recovered, typeable results at all 13 core CODIS STR loci were obtained from treated bloodstains and controls. The results from STR typing indicate that there was no evidence of DNA degradation.     

Practical applications of genotypic surveys for forensic STR testing

Legitimate genotype frequency estimation for multiallelic loci relies on component allele frequencies, as population surveys represent only a fraction of possible DNA profiles. Multilocus genotypes from two ethnic human populations, African American (n=195) and U.S. Caucasian (n=200), were compiled at 13 STR loci that are used worldwide in forensic investigation (D3S1358, vWA, FGA, D16S539, TH01, TPOX, CSF1PO, D8S1179, D21S11, D18S51, D5S818, D13S317, and D7S820). Sex-specific AmpFlSTR multiplexes provided stringent PCR-based STR typing specifically optimized for multicolor fluorescence detection. Heterozygosity at each STR locus ranged from 0.57 to 0.89 and encompassed from seven (TH01) to twenty-one (D21S11) alleles. Homozygosity tests, tests based on the distinct numbers of observed homozygous and heterozygous classes, log likelihood ratio tests, and exact tests assessed that the degree of divergence from theoretical Hardy-Weinberg proportions for all 13 STRs does not have practical consequence in genotype frequency estimation. Departures from linkage equilibrium, between loci, that imposed significance to forensic calculations were not indicated by observed variance of the number of heterozygous loci or Karlin interclass correlation tests. For forensic casework, reliable multilocus profile estimates may be obtained from the product of component genotype frequencies, each calculated through application of the Hardy-Weinberg equation to population database allele frequency estimates reported here. The average probability that two randomly selected, unrelated individuals possess an identical thirteen-locus DNA profile was one in 1.8x10(15) African Americans and one in 3.8x10(14) U.S. Caucasians.     

Heroin impurity profiling. A harmonization study for retrospective comparisons

Three laboratories present a harmonised system for the retrospective comparison of south west Asian heroin. It consists of an improved gas chromatographic (GC) profiling method and a computerised data retrieval. The investigations of the GC were necessary with a view to improve the reproducibility of the system. The necessity of a strict quality control is emphasized. The peaks of the GC profile were investigated for abundance, intensity, GC behaviour (reproducibility) and correlations; 16 of them were selected for describing the heroin profile in the database. The results from intra-lab profile comparisons are reported. The reproducibility of the analysis was good and the variation between the samples was large, thus, allowing conclusions with a high degree of certainty. The criteria of similarity were defined. The system is successfully running in all three labs.In connection with inter-laboratory comparison, the aspects of method harmonisation and standardisation are discussed. It appeared that the GC method is a very subtile one, urging for a strict standardisation between the three labs. Despite a long cooperation between three well-equipped and experienced labs, a more or less serious loss of reproducibility was noticed in the inter-lab results in comparison with the intra-lab results. The loss could for the greater part be attributed to the (limits of the) GC technique; a number of compounds, necessary for making the discrimination between samples, showed difficult chromatographic behaviour, leading to insufficient inter-lab reproducibility. Using the actual variables, improvements in performance can hardly be expected in the near future. The loss of reproducibilty implies that the number of false positive matches in a database search increases. This may strongly reduce the value of a relatively large, international database. The study shows that so far, the best option for international comparison is the analysis in a central laboratory. The idea of local determination at a large number of national labs and the use of a common database is not a realistic aim for this type of analysis.     

Population genetics of the STR loci HUMCSF1PO, HUMF13A01, HUMFES/FPS and D12S391 in Asturias (northern Spain)

In order to use genetic loci in forensic identity testing, some population data are needed. This paper presents a report of allele frequency data for the loci HUMCSF1PO, HUMF13A01, HUMFES/FPS and D12S391 in a population sample from Asturias (northern Spain).No deviation from the Hardy-Weinberg equilibrium was detected in any of the four markers investigated and there was no evidence of association between the alleles of these loci. Statistical analysis was also carried out to obtain some parameters of medico-legal interest and comparative studies were carried out with other populations studied to date for these loci. The Asturian sample does not differ substantially from other Caucasian and Spanish populations.     

Analysis of primer residue from lead free ammunition by X-ray microfluorescence

In forensic science, the analysis of gunshot residues was traditionally done by the detection of lead (Pb), antimony (Sb) and barium (Ba) usually found in a primer. However, the recent development of lead-free ammunition represents a new challenge for ballistic specialists. This analysis study gunshot residues from primers and ammunitions in the area surrounding bullet holes, a very important tool to determine the shooting distance. The ammunitions used were 9 mm Luger and .38 spl + p calibers, where lead in the primer was replaced with strontium (Sr) and where the lead bullet was plated with copper (Total Metal Jacket). Gunshot analysis results were obtained using an energy dispersive X-ray microfluorescence spectrometer. The method allows the detection and quantification of strontium residues on the target up to a distance of 45 cm.     

Cervical findings and petechial hemorrhages in falls from high positions

Cases of combined suicide are infrequent findings, especially cases in which each method can be lethal. In interpretation of cases with a multitude of serious injuries it might be impossible to discover minor injuries which had occurred in the course of a preceding confrontation, because they may be masked by the general traumatization. In two cases of suicidal fall from a height neck injuries and petechial bleedings were found. The first case (woman 53 years) was a combination suicide (strangulation by ligature, deep incisions into her wrists, jump out of the window). The intensive petechial bleedings in the face could be explained as a result of ligature strangulation and the fracture of a lower thyroid horn as an indirect fracture resulting of the head traumatization. In the second case (girl, 14 years) petechial bleedings in the face were found. Furthermore the victim had marks on her neck-skin, consisting of well-lined bleedings and scratches, presenting a clear pattern, which could be related to a necklace. An explanation of these injuries as a result of a direct impact could not be given. Something must have happened prior the fall. Informations concerning the last hours before her suicide could not be obtained but a strangulation-attempt (by herself? by others?) must be ascertained. The histological investigation of the skin of this region arised a negative vital reaction, therefore a very short interval between that event and the death was assumed.