Challenges of DNA profiling in mass disaster investigations.

In cases of mass disaster, there is often a need for managing, analyzing, and comparing large numbers of biological samples and DNA profiles. This requires the use of laboratory information management systems for large-scale sample logging and tracking, coupled with bioinformatic tools for DNA database searching according to different matching algorithms, and for the evaluation of the significance of each match by likelihood ratio calculations. There are many different interrelated factors and circumstances involved in each specific mass disaster scenario that may challenge the final DNA identification goal, such as: the number of victims, the mechanisms of body destruction, the extent of body fragmentation, the rate of DNA degradation, the body accessibility for sample collection, or the type of DNA reference samples availability. In this paper, we examine the different steps of the DNA identification analysis (DNA sampling, DNA analysis and technology, DNA database searching, and concordance and kinship analysis) reviewing the "lessons learned" and the scientific progress made in some mass disaster cases described in the scientific literature. We will put special emphasis on the valuable scientific feedback that genetic forensic community has received from the collaborative efforts of several public and private USA forensic laboratories in assisting with the more critical areas of the World Trade Center (WTC) mass fatality of September 11, 2001. The main challenges in identifying the victims of the recent South Asian Tsunami disaster, which has produced the steepest death count rise in history, will also be considered. We also present data from two recent mass fatality cases that involved Spanish victims: the Madrid terrorist attack of March 11, 2004, and the Yakolev-42 aircraft accident in Trabzon, Turkey, of May 26, 2003.