The most common type of mutation or variation found in mtDNA is called a “SNP” (stands for single nucleotide polymorphism). A SNP occurs when a single letter (nucleotide) in the DNA code is replaced with a different nucleotide.
For example, in this diagram, the “T” at location 40 is replaced by a “G.”
This mutation is documented as follows:
Location: 40
Nucleotide Change: T>G (also indicated as T40G)
In your mtDNA results report, your genetic variations will be documented the same way. These are all variation from the revised Cambridge Reference Sequence.