A definition of the nomenclature of allele variants and a description of allele polymorphism within a molecular-genetic individualization system based on the pentanucleotide tandem replication of HUMCD4

While analyzing the available published data, we found significant differences in definition of alleles of the HUMCD4 polymorphic chromosome locus. It is an obstacle for comparing the expertise results obtained while using the locus as molecular individualization system in different laboratories and, as a consequence, it hinders the use of the said marker in building up a reference database. The structure of the HUMCD4 locus was analytically investigated and the distribution of the locus alleles was systemized in a sample of 407 persons (citizens of Russia who are not blood relatives) within the present case study for the purpose of a detailed definition of its allele's characteristics. We worked out recommendations related with the nomenclature standardization of alleles of the HIMCD4 locus and specified the main population features of the locus polymorphism on the bases of the studied sample of Russia's citizens. The results can be used as reference parameters in interpreting the findings of the molecular-genetic identification expertise and examinations and in building up databases.     

Typing of mitochondrial DNA from isolated cells of the human buccal epithelium

The authors have developed a method for molecular-genetic analysis of DNA from isolated cells for the purpose of forensic medical diagnostics. The method is based on the use of the laser capture microdissection (LCM) technology in combination with typing of mitochondrial DNA. Optimization of the conditions for amplification of polymorphic mtDNA loci in preparations containing minimal amounts of the genetic material was accomplished at the initial stage of the work. To this effect, the two-round polymerase chain reaction was employed that allowed the amplified material to be accumulated in the amount sufficient for sequenation. At the next stages, the system thus obtained was tested on the cell model (using isolated cells of human buccal epithelium). It was shown that the proposed method is suitable for the analysis of specific mtDNA characteristics in a single human cell.     

Study of species specificity of the amelogenin system for genetic sex determination

The properties of amelogenin amplification system and, in particular, of its species specificity, were studied. DNA preparations extracted from cattle (cow/bull), pig, ram and from poultry (hen), as well as from dog and cat, were used as a matrix for polymerase chain reaction (PCR) involving a standard scheme of enzymatic amplification of the amelogenin gene. It was demonstrated that, unlike for the human DNA, the amelogenin test couldn't be used for the DNA of examined animals as a sex-specific marker. However, there is a danger of a false determination of the male sex in the female origin samples during a forensic-experts' typing of the amelogenin gene, if there is an admixture of an animal DNA to a human DNA preparation. As for the biological samples of the animal origin, there is a possibility of a false-female sex determination. It can be attributed to an incorrectly selected standard of the molecular weight or to its remote location on the gel as well as to the use of an inaccurately calculated algorithm designed for determining the sizes of analyzed fragments.     

Research of potentially linked variation of polymorphism of chromosome DNA in aspect of forensic expertise using molecular-genetic individualizing systems CD4, vWA and vWFII

Investigated within the case study are parameters of disbalance of lineage (HC) for 4 micro-satellite locuses of human genome: LPL, CD4, vWA and vWFII. The above locuses are widely used, both in Russia and abroad, in molecular-genetic applications for personality identification. Meanwhile, according to cytogenetics criteria, CD4, vWA and vWFII, are located close to each other in the telomeric region 12pter-12p12 in the short chromosome 12 arm, therefore their potential genetic interdependence is still a topical issue. We found a reliable HC between locuses vWA and vWFII. Locus CD4 did not display HC with locuses vWA and vWFII or with locus LPL. The latter, which is located in chromosome 8 and which must have been negative control for HC, was shown to have no HC with any of the studied markers. Such results correlate well with data on the relative physical localization of CD4, vWA, vWFII and LPL. Multiplication of frequency of alleles (genotypes) is not acceptable in typing locuses vWA and vWFII within one multi-locus panel due to the genetic linkage of these markers demonstrated within the present case study, which is an important practical conclusion.     

Optimization of the biological microchip for genotyping the AB0 locus: analytical aspects

The present work continues the search for methodological options facilitating the improvement and optimization of the biological microchip designed for genotyping the AB0 locus. It was shown in an earlier study designed to test a prototype biological microchip using a reference set of preparations with the known group specificity that under certain conditions some cells of the biochip appear to generate artifact hybridization signals that tend to make the results of genotyping either incorrect or difficult to interpret. We performed the correction of the molecular structure of DNA probes of the prototype biochip for the purpose of optimization of their hybridization potency. In addition, we developed and synthesized new DNA probes and designed new variants of the biochip. The experimental analysis of hybridization properties of all DNA probes thus obtained was carried out for the final choice of the most promising options suitable for the creation of the optimized biochip.     

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).     

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.     

Allele polymorphism of molecular-genetic individualizing systems based on tetranucleotide tandem repeats LPL,vWA and TH01 among the population of Russia

Until recently, data bases on incidence rates of alleles STR (LPL, vWA and THO1 loci) have not been introduced in Russia. To obtain information on the above rates in Russia, a large scale research of distribution of LPL, vWA and Tho1 loci has been performed among a sample of 442 blood-unrelated persons from 57 regions of the Russian Federation to specify basic assessment characteristics of these loci and to raise efficiency of expert use of identifying systems on their base. Relevant parameters (allele frequencies) are presented for each polymorphic locus as well as basic population characteristics of polymorphism in the studied sample of RF population. These results can be used as key parameters for standard probability estimations in assessing the results of molecular-genetic identification.     

Properties of the molecular-genetic individual identification system on the basis of D1S111 locus in terms of forensic-expert typing of DNA

The article presents a comparative analysis of reference nucleotide sequences for locus D1S111, estimation of basic parameters of this locus polymorphism in the representative sample of Russian population for use as an individual identification molecular-genetic system in forensic expert examinations.