Reproducibility of mtDNA analysis between laboratories: a report of the European DNA profiling group (EDNAP)

The aim of this collaborative exercise was to determine whether uniformity of mtDNA sequencing results could be achieved among different EDNAP laboratories. Laboratories were asked to sequence mtDNAHV1 region (16024–16365) from three bloodstains, proceeding in accordance with the protocol and strategies currently used in each individual laboratory. Cycle sequencing was used by 11 laboratories and solid phase single stranded sequencing was used by one laboratory. Different PCR strategies and PCR conditions were used by the different laboratories. Three laboratories used semi-nested PCR, two nested PCR, three direct amplification of HV1 and four amplification of overlapping fragments covering the HV1 region. Despite the diversity of methodologies used, all the laboratories reported the same results. The successful result of this exercise shows that PCR based mtDNA typing by automated sequencing is a valid, robust and reliable means of forensic identification despite the different strategies and methodologies used by the different laboratories.