World Trade Center human identification project: experiences with individual body identification cases.

AIM: To present individual body identification efforts, as part of the World Trade Center (WTC) mass disaster identification project. METHODS: More than 500 samples were tested by using polymerase chain reaction (PCR) amplification and short tandem repeat (STR) typing. The extent to which the remains were fragmented and affected by taphonomic factors complicated the identification project. Anthropologists reviewed 19,000 samples, and detected inconsistencies in 69, which were further split into 239 new cases and re-sampled by DNA specialists. RESULTS: The severity and nature of the disaster required an interdisciplinary effort. DNA profiling of 500 samples was successful in 75% of the cases. All discrepancies, which occurred between bone and tissue samples taken from the same body part, were resolved by re-sampling and re-testing of preferably bone tissue. Anthropologists detected inconsistencies in 69 cases, which were then split into 239 new cases. Out of 125 "split" cases, 65 were excluded from their original case. Of these 65 cases, 37 did not match any profiles in M-FISys, probably because profiles were incomplete or no exemplar for the victim was available. Out of the 60 remains not excluded from their original case, 30 were partial profiles and did not reach the statistical requirement to match their original case, because the population frequency of the DNA profile had to be </=1 in 10(9) for men and </=1 in 10(8) for women. CONCLUSION: Due to transfer of soft tissue and other commingling of remains, DNA testing alone would have led to problems if only soft tissue would have been tested. This was one of the reasons that forensic anthropologists were needed to evaluate the consistency between all linked body parts. Especially in disasters with a high potential for commingling, the described anthropological review process should be part of the investigation.