Here is the explanation of mitochondrial disease genetics by the experts:
Inheritance and Genetics
The Genetics of Mitochondrial Disease
If you or your child has been told they have mitochondrial disease it is important to find out what type of inheritance pattern the geneticist believes or knows is happening. You should also ask them who in the family needs to be told for medical reasons and what exactly you should tell them. Genetics doctors and their staff should be very adept at helping you. They are dealing with not just mito but many other genetically passed diseases everyday. It still all comes down to you having to talk to your family.