Identification of human remains by immobilized sequence-specific oligonucleotide probe analysis of mtDNA hypervariable regions I and II

Aim. A rapid analysis of mitochondrial DNA (mtDNA) sequences with an array of immobilized sequence-specific oligonucleotide (SSO) probes was tested on 18 skeletal elements recovered from mass graves in Croatia, which could not be genotyped with common forensic nuclear DNA systems (PM + DQA1 and short tandem repeat analysis). Methods. We used duplex polymerase chain reaction (PCR) amplification of the mtDNA hypervariable regions I and II (HVI and HVII) (444 bp and 415 bp amplicons, respectively) and subsequent linear array typing, which targets six polymorphic regions and two additional sites within the human mtDNA HVI and HVII. The remaining amplified products were subjected to direct sequence analysis to obtain complete sequence information for the targeted HV regions. Result. Duplex PCR amplification of the mtDNA HVI and HVII was successful in providing sufficient product for typing with the array of SSO probes in 14 out of the 18 sample extracts. We report here the sequence match of one set of remains with a panel of immobilized SSO probes, followed by direct sequence analysis. The corresponding mtDNA haplotype obtained for the bone sample and the putative maternal reference was unique in a database of 105 randomly selected Croatian individuals. Conclusion. Mitochondrial DNA typing with an array of immobilized SSO probes can be a benefit to forensic DNA analysis of mass disaster remains and identity testing of single and mass graves.