http://www.unm.edu/~gurven/_mutate/mutpap.pdf
A direct observation of hypervariability in the mtDNA control region comes from
Howell et al. (1996). They detected mutations in the NADH-dehydrogenase 6 gene in
relatives afflicted with Lebers hereditary optic neuropathy, which resulted in estimates of
mutation rate up to 200-fold higher than those estimated from phylogenetic inference.
Whether or not this increase represents a localized abnormality in mitochondrial
metabolism that would be selected against and, thereby, not appear to be significant in
phylogenetic analyses, is not known (Pääbo, 1996). This study was also important in
highlighting the realistic possibility for intra-individual variation in mtDNA. A similar
result comes from Parsons et al. (1997), with implications on interpreting alternative
scenarios of human evolution discussed in Loewe and Scherer (1997).
Howell, N., I. Kubacka, and D.A. Mackey. 1996. How rapidly does the human genome
evolve? Am. J. Hum. Genet. 59:501-515.
Pääbo, S. 1996. Mutational hot spots in the mitochondrial microcosm. Am. J. Hum.
Genet. 59:493-496.
Parsons, T.J., D.S. Muniec, K. Sullivan, N. Woodyatt, R. Alliston-Greiner, M.R. Wilson,
D.L. Berry, K.A. Holland, V.W. Weedn, P. Gill, and M.M. Holland. 1997. A
high observed substitution rate in the human mitochondrial DNA control region.
Nat Genet. 15:363-368.
Loewe, L., and S. Scherer. 1997. Mitochondrial Eve: the plot thickens. TREE. 12:422423.