Typing of STR locus in biological objects with pronounced degeneration: analysis of DNA in exhumed remains of victims of war actions

The authors describe some specific features of enzymatic amplification typing of DNA preparations obtained from degraded tissues of remains of humans, which were brought from regions of war actions in the Chechen Republic. Special attention is paid to the specific artefact of polymerase chain reaction, for the first time detected by the authors in examinations of the above-mentioned objects. This so-called "ladder" effect manifesting by simultaneous nonspecific amplification of many variants of allele fragments of the STR locus on the individual DNA matrix, which can be erroneously interpreted as an evidence of mixed DNA preparation, is apparently characteristic of individual objects with pronounced degradation of biological material. Such phenomena were observed in typing of STR locuses in biological tissues subjected to biological, thermal, and physicohemical degradation. The phenomenon was studied in detail.     

Computer analysis of face and skull size by "quantitative verbal portrait" method

The aim of this study was to develop a "quantitative verbal portrait" method on the basis of universal measured signs of the face and skull. The database includes 90 cases with expert evaluation of photocompatibility with proven identity. Four groups of signs were investigated: DX and DY--the width and height between accurately fixed concrete craniometrical (facial) points and the so-called RX and RY indices--the ratio between distances within the framework of the same direction. The proposed scheme of evaluation helps compare the photograph of a live human and the skull. For evaluating the degree of identity, one should have a summary characterization of all selected signs for the skull and compare it with the sum on the photograph; sometimes it is possible to rule out the identity of the photograph and the skull by the absolute size, e.g., a very large skull cannot belong to a human with a very little face. The score for each group of signs is used for analysis of the information for detecting the similarities. Accumulation and comparative analysis of two information flows are possible: database on portraits of lost subjects and database on graphic images of the skulls of unidentified corpses.     

Verification of amplified DNA profiles by electrophoresis in various gels

Differentiation of genotypical mixtures resultant from amplification analysis of mixed DNA preparations and false multi-strip profiles, which can result from amplification typing of individual DNA under certain conditions and simulate mixtures, impedes the molecular genetic identification expert evaluations. This paper offers an effective method for verification of amplification profiles of DNA, which is based on the use of alternative gel electrophoretic systems. This methodological approach helps detect the polymerase chain reaction artefacts without using additional expert material and promotes correct interpretation of expert findings even in difficult cases.     

Possible differentiation of mitotypes in mixed biological subjects based on phylogenetic analysis of mitochondrial DNA

A possibility was investigated to use the phylogenetic analysis of mitochondrial (mt) DNA to differentiate between the mito-types in mixed subjects in forensic medical examinations. The suggested methodological approach is based on the use of electrophoregram and on the comparison of such data with the information about phylogenic individual (mt) DNA lines.     

Results of applying molecular-and-genetic markers of chromosomal DNA in identification of unrecognizable remains of servicemen lost in military actions in the Northern Caucasus

The results of applying molecular-and-genetic markers of chromosomal DNA in identifying unrecognizable remains of servicemen lost as dead in 1994-1996 and 1999-2001 military campaigns in the Northern Caucuses are summarized in the paper. Some of the specific features related with enzymatic amplification typing of DNA preparations sampled from degraded biological tissues of strongly deformed or decayed cadavers were analyzed. The typing results were analyzed by the AB0 system of degraded expertise samples in order to check the reliability of routine forensic-biological examinations as applicable to cadaver tissues with pronounced putrefactive changes. It was established that group-specific antigens of the AB0 system were correctly determined only in 67.5% of cases. False results were obtained in the other 32.5% of cases. Most of them were related with determination of groups 0(I) and A(II).     

Possible difficulties in molecular-genetic expertise in cases with insufficiently high individual significance of the results (as exemplified by a complex case with disputable maternity)

Molecular genetic technologies used in forensic medical expert evaluations help quantitatively evaluate the significance of coincidence or non-coincidence of signs in personality identification and in expert evaluation of kinship identification (disputable paternity or maternity). The level of validity of evidences, which can be considered necessary and sufficient, is the principal problem in such cases. Analyzing a complex case with disputable maternity, the authors discuss problems illustrating the necessity of attaining a high level of validity of the results for drawing a justified expert conclusion. Only high validity standard can rule out errors in interpretation of the results, otherwise the significance of the detected complex of signs can be insufficient for an unambiguous solution of an expert task.     

Whole-genome amplification by MDA to improve sensitivity of forensic expert examination of chromosomal DNA

This pilot project has the objective to evaluate the possibility of application of the multiple displacement amplification (MDA) technique to whole-genome amplification with a view to improving sensitivity of molecular-genetic test-systems. Preparations of total cellular DNA were amplified by MDA and analysed to assess conserved specificity of chromosomal DNA and its enhanced template activity in the standard polymerase chain reaction (PCR) for typing allele variants of polymorphous DNA loci. DNA samples before and after MDA showed virtually identical genotypic combinations of alleles. Allele fragments were stably detected at a level of DNA 4-5 times lower than in the standard test. The results of the study indicate that the MDA technique provides a promising tool to improve reliability of forensic- expert examination of chromosomal DNA and imply the necessity to further develop forensic-medical aspects of this method.     

Typing of ABO locus with biological microchip as a new level in solution of problems in forensic-medical biological expertise of material evidences

There are cases in practice when during expertise of material evidences, discrepancies between results of typing of ABO antigens and molecular-genetic typing of DNA occur. In this work, as a radical approach to objective solution of similar conflict situations, for some contradictory case of expertise, all examinations were performed on the unified methodological base--DNA level. Instead of biological (isoserological) typing of ABO antigen, molecular-genetic typing of ABO locus with biological microchip was performed. In all cases the results, received with the use of biological microchip, do not contradict but completely conform to the results of others molecular-genetic examinations performed in the case. Given results indicate irrationality of further use of traditional methods of isoserological typing of ABO antigen for primary differentiation of biological material. These analyses, if necessary, have to be performed on DNA level with molecular-genetic expertise.     

The selective spatial filtration of roentgenograms in the forensic medical expertise of stab-cutting wounds]

Investigation of 14 roentgenograms of skin preparations with cut-stab wounds, treated by spatial filtration method in medium and high spatial frequency modes was performed using material of 13 specific cases. This resulted in detection of disturbances of skin pattern left at the area of former skin cone in 7 cases while in 2 cases indistinct heel traces were seen. Changes in skin pattern were not recorded on roentgenograms of skin preparation of 12 experimental cut-stab wounds obtained on cadaveric skin.     

Analysis of clonidine in biological fluids using gas chromatography with an electron capture detector

The method of clonidine identification in blood and urine is described. It is based on liquid-liquid extraction and purification with toluol, subsequent derivation with pentafluobenzoylchloride and test on gas chromatograph with a detector of electron capture. The method is proposed for expert examinations.