Post-mortem forensic identity testing: application of PCR to the identification of fire victim

abstract CONTEXT: DNA analysis has been used with success in the identification of carbonized corpses and victims of large accidents. The analysis requires relatives of crash victims to donate blood for analysis. The relatives are generally willing contribute to the identification by giving a blood sample. OBJECTIVE: To describe the use of the polymerase chain reaction (PCR) for genetic characterization of one victim extensively burned by fire. DESIGN: Case report. CASE REPORT: DNA was extracted from blood of the cardiac chamber, and 15 different loci (D1S80, ApoB, D17S30, D3S1744, D18S849, D12S1090, FGA, D7S820, D1S533, D9S304, HUMCSF1PO, HUMTPOX, HUMTHO1, amelogenin and HLA-DQA1) were analyzed using the PCR technique. Results from all loci typing of the corpse were then compared to that of his alleged biological parents, revealing a genetic compatibility.


INTRODUCTION
DNA typing techniques are one of the most advanced tools for human identification. 13][4] The success and validation of a criminal investigation are very closely related to the process used for obtaining and preserving biological evidence. 5][14][15] In severely charred fire victims both autolytic changes as well as deleterious effects of heat will cause degradation of the DNA. 16olymerase chain reaction (PCR) procedures permit reliable replication of thousand of copies of a specific DNA sequence, in vitro, and have been described and improved in recent years, [17][18][19] allowing the study of small amounts of DNA even when degraded.These procedures are therefore extremely useful in the analysis of forensic samples.Several loci are especially suitable for PCR analysis.DNA analysis has been used with success in the identification of carbonized corpses and victims of large accidents. 16,20,21The analysis does, however, require relatives of crash victims to donate blood for analysis.It is found that the relatives are generally willing to contribute to the identification by giving a blood sample. 21his paper describes the use of PCR for genetic characterization of one victim extensively burned by fire.
extracted from blood of the cardiac chamber of this corpse.

Scenario
During a recent police chase following a kidnapping, a car crashed and burned.An intensely burned corpse was removed from the car and sent for forensic identification.There were no fingerprints or other ways to identify the corpse, but there was a suspicion about its identity.To confirm this hypothesis, the DNA of the alleged parents was compared to the DNA extracted from the burned corpse.

Procedures
DNA was extracted from blood of the cardiac chamber of the carbonized corpse by the Kunkel method 22 and from 5 ml of peripheral blood obtained from the alleged biological parents of the corpse by the salting-out procedure. 23The D1S80 locus was studied using the D1S80 Forensic DNA Amplification Reagent Kit (Perkin Elmer, USA), as recommended by the manufacturer.The amplified fragments were submitted to electrophoresis on a polyacrylamide gel (GeneAmp Detection Gel -Perkin Elmer) and visualized after silver staining.Allele identification was achieved by comparison of the amplified fragments to the allelic ladder included in the kit.The study of the HLA-DQA1 locus and the analysis of the alleles were performed using the Amplitype HLA-DQA1 Forensic DNA Amplification and Typing Kit (Perkin Elmer, USA), as recommended by the manufacturer.The amplification and analysis of the D3S1744, D18S849, D12S1090, FGA, D7S820, D1S533 and D9S304 loci were assembled using the components of the Multiplex I and Multiplex II Kits (Lifecodes Corp., USA).The CTT Multiplex Kit and Amelogenin Kit (Promega Corp., USA) was used for the amplification and study of the HUMCSF1PO, HUMTPOX, HUMTH01 and amelogenin loci.The Multiplex and amelogenin kits were used as recommended by the manufacturer.The D17S30 locus was studied using primers, reactions and gel analysis as described by Horn. 24llele identification was achieved by comparison of the amplified fragments to the allelic ladder (Promega Corp., USA).The ApoB locus was studied using primers, reactions and gel analysis as described by Boerwinkle. 25 Allele identification was achieved by comparison of the amplified fragments to the 100 bp and 123 bp ladder (GIBCO-BRL, USA).The amplification products obtained from genomic DNA extracted from the blood of the corpse were compared to those generated from genomic DNA obtained from corpse's alleged biological parents.
The data obtained from the study of the 15 loci are presented in Table.

DISCUSSION
The identification of remains from fire victims is generally attempted by recognizing personal effects, individualizing marks (e.g.scars, tattoos, signs of known disease) and/or dental records.
However, due the effects of heat and severe laceration of the body, the identification by usual forensic means is not always possible.In such cases DNA may be obtained from crude tissue samples (about 1 gram), collected during autopsy, 16 from soft tissues within the nerve chamber of unerupted wisdom teeth 20 or from muscles. 21 paternity test was performed and Mendelian inheritance of the alleles for these 15 loci was observed.
The present study revealed that biological material (blood) collected from the cardiac chamber of the carbonized corpse, even with highly degraded DNA, could be analyzed by the PCR technique and positively identify the victim.
Professional workers, like detectives, prosecutors, lawyers, judges, doctors etc., who act in different forensic areas related to the solution of crimes and human identification have long had the need for an efficient method capable of positively identifying an individual.Recent advances in molecular biology have significantly enhanced the potential for individualization by providing a capability for typing DNA from various biological materials.DNA analysis has been used successfully in a number of large accidents to associate body parts and for the purposes of identification, by comparing victims' DNA profiles with those of relatives.In this sense, molecular biology has become an important and fundamental tool for personal investigation.

Table - Genotypes identified in the three DNA samples
A análise do DNA tem sido utilizada com sucesso na identificação de carbonizados e de vítimas de grandes acidentes.A análise do DNA necessita de amostras de sangue dos familiares das vítimas como referência.Os familiares normalmente contribuem com a identificação doando uma amostra de sangue.se a técnica da PCR.Os resultados de todos os loci analisados a partir de DNA genômico extraído do corpo carbonizado foram comparados com os resultados obtidos a partir de DNA genômico extraído de sangue dos supostos pais biológicos do corpo, revelando uma compatibilidade genética.