RESUMEN
The authors report the results of the demonstrative study continuing the cycle of interactive discussions pertinent to the possibility of obtaining reliable genetic information from the analysis of burnt bone fragments. Special emphasis is placed on the worthiness of these materials for genotyping of mitochondrial DNA (mtDNA) with the use of the standard analytical methods employed for the purpose of forensic medical expertise to investigate into the length polymorphism of the amplified mtDNA fragments (PAF) by means of sequencing with fluorescent detection. The study has demonstrated that the mtDNA fragments in the state suitable for genotyping can be found only in the preparations from the bone tissue exposed to the 'mild' thermal impact after which the affected bone is virtually indistinguishable from the native one as far as the outward appearance is concerned. In the cases of a more rigorous thermal impact when the bone tissue exhibits well pronounced signs of heat destruction, it should be considered as inherently unsuitable for genotyping of mtDNA. It was shown that chromosomal DNA is inferior to mtDNA in terms of heat resistance. This finding agrees with the currently adopted view, however this advantage of mtDNA is relatively insignificant from the standpoint of genotyping efficiency.
Asunto(s)
Huesos , Quemaduras/patología , ADN Mitocondrial , Antropología Forense/métodos , Genética Forense/métodos , Huesos/lesiones , Huesos/patología , ADN Mitocondrial/análisis , ADN Mitocondrial/genética , Humanos , Biología Molecular/métodosRESUMEN
The objective of the present study was a demonstrative consideration of the debatable problem concerning the possibility of obtaining reliable genetic information by the investigation of burned bones. The bone fragments with the identifiable external features of different degree of ignition (i.e. in the carbonized, grey- and white-burnt states) were placed in the muffle furnace for the controlled thermal treatment. The analytical suitability of these burned bone objects for genotyping was estimated with the use of standard chromosomal STR-loci multiplex genotyping panels. The results of the study cast serious doubts as regards the possibility of genotyping of chromosomal DNA extracted from the burned bones. It was shown that the exposure of the bone tissue to a temperature of 150 degrees Celsius during 2 hours can turn it into a material absolutely unsuitable for genotyping due to the loss of all individual genotypic traits. Characteristically the burned bone objects are externally indistinguishable from the native bone. At the same time, the material with the signs of the high-temperature impact visible by the unaided eye (e.g. in the carbonized, pronounced black as well as grey and white-burnt states) is altogether unsuitable for the reliable identification of the genetic profile of chromosomal DNA.