There are so many different types. So many symptoms and effected organs. We don't know the gene in my family causing yet because we can't get our insurance to cover the exome sequencing. Sister had positive biopsy for mitochondrial myopathy but that's as far as we have gotten. Grandfather, my dad, sister and I, and my son are affected. An aunt and uncle too. Treatment is very complex. Treat whatever symptoms there are and give a cocktail of meds for whatever deficiencies there are. I made my own post about it here too.