Figure 6. Diagram illustrating the sequence of events (I, II) capable of driving functional mitochondria to shift to a partially functional or non-functional state.

The mutational events (I) may arise as a consequence of unusual DNA conformations, fragile motifs, exogenous factors, among others. These mutations will co-exist with the wild-type mtDNA in a heteroplasmic state, or eventually be selected (II) until a homoplasmic state is reached.