Improvements to the Forensic Analysis of Mitochondrial DNA Typing

Sequence analysis of human mitochondrial DNA (mtDNA) is an effective and reliable tool for the genetic characterization of forensic samples. The nature of the mitochondrial genome (mtgenome), its high copy number and small size (~17kb) makes it more resistant to degradation and more stable than nuclear DNA. For this reason mitochondrial DNA is often the only feasible option for the forensic analysis of environmentally compromised samples. Currently the forensic analysis of the mtgenome is restricted to the hypervariable regions, also known as the Displacement loop (d-loop). Previous studies, confirmed in the Strausbaugh lab, have demonstrated an increased variability in the hypervariable regions between and amongst various populations. Within the D-Loop is the HV1, which is used forensically to include or exclude suspects. Current data suggest that analysis of the HV1 region has a low power of discrimination. However, the data is largely supported by samples of European ancestry and does not consider the variation observed in other populations. My research addresses this prediction through the evaluation of a forensically relevant population, self-identified U.S. African Americans. In several instances we were unable to amplify the region of interest due to problems with the current protocols and reagents. In order to answer the question of hypervariable region variation PCR reagents and appropriate amplification cycles had to be optimized. This research employs mtDNA hypervariable region amplification in conjunction with standard Sanger sequencing in order to evaluate the power of discrimination of mtDNA analysis. Results suggest that HV1 analysis is sufficient for many U.S. African American samples and that the power of discrimination of mtDNA analysis is based on the maternal ancestry of an individual