Evaluation of Mitochondrial DNA Typing in a Forensically Relevant Population of Self-Identified U.S. African Americans

Evaluation of Mitochondrial DNA Typing in a Forensically Relevant Population of Self-Identified U.S. African Americans Ranyelle S. Reid University of Connecticut, 2013 Abstract Analyses of hypervariable segments of mitochondrial DNA (mtDNA) are currently being used for forensic analysis, human molecular genetics, evolutionary biology, human migration studies and recovery operations in identifying deceased persons, both ancient and modern. Mitochondrial DNA analysis offers a unique maternal ancestral view of an individual’s molecular pin code, through typically examining the hypervariable segments and sampling the areas of hypervariable region 1 (HV1) and hypervariable region 2 (HV2). The goal of this project is to revisit the utility of mtDNA typing in forensics through the analysis of a forensically relevant population of self-identified U.S. African Americans. In Chapter 2, we asked whether a similarly low level of resolution of HV1 sequence types in Europeans mtDNA occurred in persons of ‘recent’ African ancestry. Our studies yielded remarkable variation within the mtgenomes of U.S. African Americans and, furthermore, demonstrated that mtDNA analysis, in fact, has a higher power of discrimination when applied to the U.S. African American population (n= 185); a group inadequately represented in mtDNA databases. Chapter 3 describes our efforts in the employment of recent advances in DNA typing technologies (microarray whole genome sequencing, SNP panels) to demonstrate that the mtDNA-coding region increases the resolving power of mitochondrial DNA forensic typing. We used whole genome resequencing to identify diagnostic SNPs (mtDNA variants) that would yield powerful genetic markers into refining the relationship between ethnicity and haplogroup association. Chapter 4 data illustrate that a clear majority (90%) of our samples showed concordance between self-identified ethnicity and haplogroup assignment. In the instances of ethnicity-haplogroup disagreement, we further evaluated the sample using the diagnostic SNP panel, which revealed a more accurate reflection of deep ancestry, thereby reclassifying the haplogroup and establishing concordance between the self-identified ethnicity and the haplogroup assignment. The findings of this research: improve upon the current state of knowledge of mtDNA variation in a forensically relevant population of U.S. African Americans demonstrate that the power of discrimination of mtDNA HVI typing will vary based on maternal lineage; suggest that HVI typing may be sufficient for the exclusion of U.S. African Americans; and bolster previous reports that suggest mtDNA analysis may provide new avenues for the consideration of alternative or weak suspects