Mutations in MT-TL1 (Mitochondrially encoded tRNA leucine 1)

A common mutation is A3243G. Can result in multiple mitochondrial deficiencies and associated disorders. It is associated with:

• Mitochondrial encephalomyopathy
• Lactic acidosis
• Stroke-like episodes (MELAS)

MELAS is a rare mitochondrial disorder known to affect many parts of the body, especially the nervous system and the brain. Symptoms of MELAS include:

• Recurrent severe headaches
• Muscle weakness (myopathy)
• Hearing loss
• Stroke-like episodes with a loss of consciousness, seizures, and other problems affecting the nervous system.

Source: https://en.wikipedia.org/wiki/MT-TL1

I think the point of the question is to recognize that this is a mitochondrial disease (mother and maternal grandmother were affected). Produces wide range of effects, but muscle weakness and some neurologic deficits stood out to me. Also this: https://ghr.nlm.nih.gov/gene/MT-TL1#conditions

This is a presentation of mitochondrial myopathy. They often present with myopathy, lactic acidosis, and CNS disease. 2° to failure in oxidative phosphorylation. Muscle biopsy often shows “ragged red fibers”.

There is variable expression in a population or even within a family due to heteroplasmy in mitochondrial inheritance.

It's a mitochondrial disease. - present in successive generations, always with maternal transmission - damage to high-energy tissues - CSF lactic acidosis (due to increased anaerobic metabolism due to impaired oxidative phosphorylation)

The disease is MELAS. Mitochondrial encoded tRNA leucine 1 is the mutation. Apparently associated with high tone deafness. It is apparent its mitochondrial with maternal transmission, though unfortunately the etiology is utter memorization / process of elimination. Maybe next time the stragy will focus more on mitochondiral diseases and see that this choice is the only mitochondiral answer choice.

• Mitochondrial Encephalomyopathy Lactic Acidosis Stroke like symptoms."MELAS is a rare mitochondrial disorder known to affect many parts of the body, especially the nervous system and the brain. Symptoms of MELAS include recurrent severe headaches, muscle weakness (myopathy), hearing loss, stroke-like episodes with a loss of consciousness, seizures, and other problems affecting the nervous system.[5]" Source :Wiki