mtDNA matches at all points but one. Still a relative?

Factual Questions
1

Comparing two mitochondrial DNA samples, one from 1833 and one from 2002, investgators found them to match on all points but one of the points checked. The lead investigator claims to be 95% sure the two people share a common lineage and suggests that the discrepancy could be caused by a spontaneous mutation.

Does that sound reasonable to you geneticists out there?

2

IANA professional geneticist, but it sounds reasonable to me. I couldn’t say whether 95% is the perfect figure, but it’s about right. The thing to realise is that “common lineage” doesn’t imply that the 1833 person was an ancestor of the 2002 person or even a close relative of that ancestor. Even mitochondrial DNA accumulates mutations fairly slowly and 1833-2003 can be as litle as 3 generations. The common ancestor could have been 1000 years ago. These two people may have simply come from the same continent and had no known links to one another.

3

I thought the mutation rate was like 1 base change every 10 -20k years for mtDNA. Aren’t there millions of people worldwide with the EXACT same mtDNA? I would think it would be almost meaningless, in terms of relatedness, to say that two people had the same mtDNA. If there is one base difference, then they share an ancestor long, long ago.

When you say “investigators”, what do you mean?

4

Well, my question could’ve been phrased better, too. I’m writing a Staff Report on Kaspar Hauser. The common ancestor is Stephanie de Beauharnais, the older samples are from Hauser, born around 1812 and supposedly her son, and the newer ones from Astrid von Medinger, a direct descendant of Stephanie.

5

Some of Germany’s top forensic geneticists. They won’t go too far out on a limb with their claims while other researchers, of course, say it’s a slam dunk that all three parties are closely related.

6

Here is a Warning PDF article about mtDNA change rates, someone with more knowledge of such things could give an overview of what the rate of mtDNA mutation is. The article seems to show that the rate is not known to better than a few orders of magnitude.

Mitochondrial DNA is an extremely interesting subject, and one I didn’t even know the existance of until very recently. I would hope many dopers take an interest in mtDNA and its implications.
http://en.wikipedia.org/wiki/Mitochondrial_DNA