What sort of mutations occur in mitochondrial DNA?
The majority of the changes that occur in the DNA sequence are known as “transitions”; i.e., an “A” changes to a “G”, a “G” changes to an “A”, a “C” to a “T”, or a “T” to a “C”. A much rarer sort of mutation, called a transversion, involves a change of an “A” to “T” or “C”, a “G” to “C” or “T”, a “C” to “A” or “G”, and a “T” to “G” or “A”. The most informative way to describe a polymorphism is to list the reference base, the position, and the polymorphic base A16501, for example, which is characteristic of memebers of haplogroup U2. There is a common practice in the literature of noting a transition simply by the position of the mutation – thus the mutation of the A at position 16501 to a G is simply noted “16051”. Transversions are often annotated with the resulting base change as part of the designation. For example, the mutation of the A at position 13101 to C, diagnostic for haplogroup H8, is often written A13101C, or more concisely as 13101C (since position 13101 is defined as A i
