MS-2022

A couple has approached you for genetic counselling. The husband, Felix, is worried about passing on a mitochondrial disease to his future child as his sister died at a young age due to complications associated with the same disease. The wife, Melissa, has no family history of any such disease. Both parents identify as cisgender.

Felix undergoes testing for the mitochondrial disease, and the results come back positive.

What is the probability of their first child being affected by this mitochondrial disease?