In every human cell, there are hundreds and sometimes thousands of mitochondria. Each mitochondrion has
several copies of its genetic code (represented by the letters A, C, T, and G). This genetic code is mitochondrial
DNA (mtDNA) and tells the mitochondria how to function. The code also tells the mtDNA how to copy itself. Over
time, the copying process can create small changes - the “polymorphisms” or “mutations.” If these changes are in
the mother’s egg cell, the child produced from that egg inherits them. If female, the child may some day pass that
same change on to her own children.
Slowly, these changes build up down maternal lineages. They define and mark branches on the maternal tree. We
can look at your specific mtDNA code sequence to see which changes you have in your mtDNA.
There are two scientific baseline sequences to which scientists compare these changes in mtDNA: the
Reconstructed Sapiens Reference Sequence (RSRS) and the revised Cambridge Reference Sequence (rCRS). By
comparing your mtDNA changes to each sequence, we can distinguish the differences between the original values
in the RSRS (or the comparative values in the rCRS) and your test results. Following scientific standards, Family
Tree DNA compares all mtDNA results to the rCRS, and provides you with your comparisons to the RSRS