What is the most likely transmission mechanism for the passage of leigh syndrome from parent to child?

Pattern of inheritance described in the prompt is one which females transmit leigh syndrome to all of their offspring. That is, the leigh syndrome is a maternally transmitted disorder. Because it is also a cytoplasmically inherited disorder, it will be transmitted through cytoplasmic components, such as mitochondria. Leigh syndrome is transferred through organelles in the cytoplasm rather than through DNA in the nucleus.

Mitochondria produce atp, a high energy compound. atp is used for all sorts of enzyme-mediated reactions, such as making proteins/nucleotides/etc, certain compounds cross the cell membrane, muscles move, etc.  without this source of energy, a cell will die. it will not be able to repair itself, defend against pathogens, etc.