fig1

Figure 1. A: mtDNA mutations affect transcription, translation, enzyme complex, biochemistry, and cellular phenotype at different levels. These mutations may give rise to homoplasmy or heteroplasmy conditions, which can result in a disease or normal phenotype, known as a phenotypic threshold effect; B: The energy production process via oxidative phosphorylation (OXPHOS) may also lead to the formation of reactive oxygen species (ROS) in the electron transport chain. Oxidative stress conditions could further lead to the destruction of macromolecules, such as lipids, proteins, and DNA. Modified from a previous publication^[16]