SMGF tests mtDNA at over 1000 locations. The base value for each location is compared with the CRS (Cambridge Reference Sequence). Locations and differences in base values called "mutations" are stored in the mtDatabase.
The mtResults screen will show matches in the mtDNA to the mutations you entered on the search page. Results will also be filtered based on your input parameters.
Exact Matches: An exact match indicates another participant has the same mtDNA values that you entered. An exact match may mean that you share a common maternal ancestor in genealogical time (the last 500 years).
You should always view the pedigrees of exact matches to see if you share a common ancestor in the maternal line.
However, an exact match may also mean you share a common ancestor before genealogical time. These distant matches may be of "deep ancestry" interest, but may not help extend your genealogy in more recent time.
One Difference: These are matches with another participant who has a difference of one mutation from your entry on the search page. Matches with one difference may on rare occasions mean that you share a common maternal ancestor in genealogical time.
You may wish to look at matches with one difference, especially if your pedigree extends over many generations. You may on rare occasions find a common ancestor in the maternal line.
Two Differences: These are matches with another participant who has a difference of two mutations from your entry. Matches with two differences almost never indicate a common maternal ancestor within genealogical time, but may be of "deep ancestry" interest.