L1c2b1a, the (African) Haplogroup With The Longest Mitochondrial Genome!K. H. Ritchie, U. A. Perego, A. Achilli, N. R. Angerhofer, N. M. Myres, A. Torroni, S.R. WoodwardAbstract
Haplotypes derived from the maternally-inherited mitochondrial DNA (mtDNA) control region are often employed as a first step in determining phylogenetic-relevant samples that could be selected for additional coding region testing. Using the currently defined world mtDNA haplogroup tree, researchers can assign these haplotypes to specific branches, paying particular attention to novel mutations that could assist in identifying new subclades. Because of the high mutation
rate characteristic of the mtDNA hypervariable region, recurrent and back mutations are observed frequently and therefore some haplogroups are more difficult to predict with these data only. However, several haplogroups have been confirmed through mutations in the control region, such as the Native American C1b branch characterized by the transition at np 493. During a recent survey of the nearly 58000 mtDNA control region haplotypes currently available in the publicly accessible Sorenson Molecular Genealogy Foundation database, we observed a small number of mtDNAs (n=16) characterized by the presence of unusually long insertions. A small subset of these particularly long mtDNA haplotypes shared an identical insertion of 15 bases. Genealogical analysis combined with haplogroup prediction confirmed that these haplotypes shared a common African origin. Additionally, based on the pedigree data gathered, we determine the donors were not closely related. Moreover, through the analysis of complete mtDNA sequences, we conclude that the newly defined haplogroup is most likely of recent origin. As reported in this study, insertions of more than 10 bps are quite rare in the general population and in the published literature, thus providing an interesting case work in population and possibly future disease studies.
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