How Useful are Genetic Ancestry Tests?

Autosomal DNA and mitochondrial DNA (mtDNA) are efficient means of predicting an individual’s genetic ancestry. Commercially available autosomal DNA ancestry estimates are obtained using loci that show large frequency differences between continental groups known as ancestry informative markers (AIMs) and mtDNA ancestry estimates rely on haplogroup information to trace an individual’s genetic lineage. Since autosomal DNA is bi-parentally inherited and mtDNA is uni-parentally inherited, autosomal DNA contains more information regarding an individual’s genetic heritage than mtDNA. Our goal is to determine the accuracy of mtDNA ancestry estimates for predicting autosomal DNA ancestry. Using a program called frappe, autosomal ancestry proportions were determined in 965 individuals from the Human Genome Diversity Project (HGDP-CEPH) for seven world regions: Africa, Middle East, Europe, Central/South Asia, East Asia, Oceania, and America. Additionally, mtDNA haplogroups were obtained for the 965 HGDP-CEPH individuals by using continent-specific restriction fragment length polymorphisms. After filtering the individuals for low ancestral proportions and inconsistent genotypes, 938 individuals were used to compare the mtDNA haplogroups to the amount of variation in autosomal ancestry proportions. Our results strongly suggest mtDNA haplogroups are not useful in predicting an individual’s ancestry, whereas autosomal DNA remains the most informative genetic tool to indicate an individual’s ancestry.