Primary Mitochondrial Myopathy

What is primary mitochondrial myopathy?

A mitochondrial myopathy is a type of mitochondrial disease that causes significant muscular problems. Mitochondrial diseases are caused by defects in the mitochondria, structures found in each cell of the body that make energy. Because muscle cells have high energy needs, a lack of mitochondria can lead to muscular problems. Primary mitochondrial myopathy can occur at any age. It is usually more severe when it appears early in life and milder when it presents later in life. It is estimated to affect about 1-2 per 10,000 people.

What are the symptoms of primary mitochondrial myopathy?

Characteristic symptoms of primary mitochondrial myopathy include the following:

• Muscle weakness
• Unusual feelings of exhaustion caused by physical exertion
• Impaired vision, including paralysis of eye movements and drooping of the upper eyelids
• Difficulty swallowing
• Slurred speech
• Abnormal heartbeat
• Nausea
• Headache
• Breathlessness
• Stunted growth
• Developmental delay
• Seizures
• Diabetes
• Heart failure
• Rarely, muscle cramping

What causes primary mitochondrial myopathy?

Human traits are inherited from a person’s father and mother; each one contributes a copy of a gene, which interacts with the other copy. When a gene mutates, it can lead to diseases. The way primary mitochondrial myopathy is inherited is often very complex. It can be inherited through a patient’s parent, but the mutation can also occur spontaneously, meaning that it occurs without any family history.

How is primary mitochondrial myopathy diagnosed?

Primary mitochondrial myopathy can be diagnosed using the following procedures:

• Thorough recording of family history
• Physical examination
• Lab tests
• Muscle biopsy
• Exercise physiology study
• CT scan
• MRI

While none of the symptoms of primary mitochondrial myopathy are unique to the disease, having a combination of three or more of these symptoms can strongly indicate its presence.

What are the treatments for primary mitochondrial myopathy?

While there is no specific treatment for primary mitochondrial myopathy, there are things that can be done to lessen symptoms. These include:

• Physical therapy to extend range of movement in muscles
• Occupational therapy
• Vitamin therapies to improve fatigue and energy levels (common therapies include: riboflavin, carnitine, creatine, and coenzyme Q)
• Surgery to lift drooping eyelids
• Speech therapy

Where can I find out more about primary mitochondrial myopathy?

• Muscular Dystrophy Association
• National Organization for Rare Disorders (NORD)
• NIH