Stacking the Deck: Mutation Rate in the mtDNA Coding Region
‘Satiable Curiosity is a column dedicated to the proposition that genetic genealogists are an untapped resource for resolving questions about DNA behavior -- how DNA changes over the course of a few or many generations and how DNA patterns are distributed around the world. Some questions are so broad that it could take decades to arrive at a conclusion, yet others are narrow enough to answer in a shorter time frame, perhaps even within a semester or two for a student research project. The results may nonetheless be of considerable genealogical utility and scientific interest, worthy of publication in a technical journal.
The scientific method emphasizes the importance of
The more orthodox approach would be to study a very large number of mother/child pairs and divide the number of mutations by the number of transmission events, but mutations are rare, and the cost would be prohibitive with current technology. Adding a genealogical component, testing descendants of a common ancestor, augments the efficiency of the effort: two people can represent a larger number of transmission events.
So far, the method does not violate the ra
As of this writing, 47 genetic genealogists have submitted their sequences to GenBank. Many of those records have “private” mutations, which can easily be identified by positioning them on a master phylogenetic tree at MITOMAP. A call for volunteers who have obtained their full sequence and who can locate a distant matrilineal cousin would doubtless bring a larger sample onboard.
The results of this pilot study would be of great interest
to genetic genealogists, who wonder how useful a full sequence test might be in
identifying branch points in descendancy charts. They would also be helpful to the scientific
community, since the results would place an upper bound on the mutation rate
and provide guidance about the size of a sample necessary to conduct a ra
Suggestions for future columns are welcome. E-mail: DNACousins (at) aol.com.
Behar DM, Metspalu E, Kivisild T, Achilli A, Hadid Y, Tzur S, Pereira L, Amorim A, Quintana-Murci L, Majamaa K, Herrnstadt C, Howell N, Balanovsky O, Kutuev I, Pshenichnov A, Gurwitz D, Bonne-Tamir B, Torroni A, Villems R, Skorecki K (2006) The matrilineal ancestry of Ashkenazi Jewry: portrait of a recent founder event. Am J Hum Genet, 78:487-497.
Figure 1 Part of the Phylogenetic Tree for Haplogroup K (Behar 2006)