Is mitochondrial disease passed down from the mother? if kiddo has it, does it mean mom has it too?

Yes: Hi. Mitochondrial disease may be passed on by the egg, but not sperm. If the kiddo has it, it came from the mother.

Complex issue: It takes 2 events to create the mitochondrial dysfunction. First the vulnerable mitochondria come along in the egg (sperm can't bring it).Then the combination of DNA formed by sperm/egg must have the wrong instructions so the mitochondria don't work right. This way mom can be unaffected and have a kid with the disorder.