Results of a collaborative study of the EDNAP group regarding mitochondrial DNA heteroplasmy and segregation in hair shafts.

A collaborative exercise was carried out by the European DNA Profiling Group (EDNAP) in order to evaluate the distribution of mitochondrial DNA (mtDNA) heteroplasmy amongst the hairs of an individual who displays point heteroplasmy in blood and buccal cells. A second aim of the exercise was to study reproducibility of mtDNA sequencing of hairs between laboratories using differing chemistries, further to the first mtDNA reproducibility study carried out by the EDNAP group. Laboratories were asked to type 2 sections from each of 10 hairs, such that each hair was typed by at least two laboratories. Ten laboratories participated in the study, and a total of 55 hairs were typed. The results showed that the C/T point heteroplasmy observed in blood and buccal cells at position 16234 segregated differentially between hairs, such that some hairs showed only C, others only T and the remainder, C/T heteroplasmy at varying ratios. Additionally, differential segregation of heteroplasmic variants was confirmed in independent extracts at positions 16093 and the poly(C) tract at 302-309, whilst a complete A-G transition was confirmed at position 16129 in one hair. Heteroplasmy was observed at position 16195 on both strands of a single extract from one hair segment, but was not observed in the extracts from any other segment of the same hair. Similarly, heteroplasmy at position 16304 was observed on both strands of a single extract from one hair. Additional variants at positions 73, 249 and the HVII poly(C) region were reported by one laboratory; as these were not confirmed in independent extracts, the possibility of contamination cannot be excluded. Additionally, the electrophoresis and detection equipment used by this laboratory was different to those of the other laboratories, and the discrepancies at position 249 and the HVII poly(C) region appear to be due to reading errors that may be associated with this technology. The results, and their implications for forensic mtDNA typing, are discussed in the light of the biology of hair formation.

Naming the Dead - Confronting the Realities of Rapid Identification of Degraded Skeletal Remains.

The Armed Forces DNA Identification Laboratory (AFDIL) is one of the leading laboratories in the world for the processing of degraded skeletal remains. Extended efforts have been made to develop protocols and standards that will hold up to the intense scrutiny of both the scientific world and the U.S. legal system. Presented in this paper are the specifics of the in-house systems and procedures that have allowed AFDIL to streamline the processing of degraded skeletal remains and family references for mitochondrial DNA (mtDNA) analysis. These include the development of our in-house bioinformatics systems by which every package and sample that passes through the laboratory is tracked; protocols designed specifically for both questioned and reference samples; and the difficulties inherent in this type of organization. Two case studies presented involve one of ancient remains and one on the recent event of September 11, 2001. Finally, future directions available to both AFDIL and the DNA analysis community as a whole are discussed.