Conditions Basics

What are mitochondrial diseases?

Mitochondrial (say "my-tuh-KAWN-dree-uhl") diseases are a group of rare diseases that can be passed down from mothers to their children. The diseases happen when mitochondria don't work the way they should. Mitochondria are tiny parts of the cells in your body. They are often called the powerhouse of a cell, because one of their jobs is to make energy.

These diseases can appear at any age. And they can affect many different areas of the body.

Examples of these diseases include:

• Kearnes-Sayre syndrome. Symptoms usually appear before the age of 20 and affect the eyes and ears.
• Leigh syndrome. It affects a baby's nervous system. It usually starts in the first year of life.
• MERRF syndrome. It affects the nervous system, muscles, and other areas of the body.
• MELAS syndrome. It affects many areas of the body, including the brain, the nervous system, and muscles.

What are the symptoms?

The symptoms of mitochondrial diseases depend on the type of cells that have damaged mitochondria. These cells include brain cells, muscle cells, and the cells of the eyes and ears. Other parts of the body that may be affected include the kidneys, nerves, and liver.

Symptoms can vary from person to person.

Brain cells

Mitochondrial disease in brain cells can cause symptoms such as:

• A decrease in mental abilities.
• Seizures.
• Strokes.

Muscle cells

When the disease is in muscle cells, the symptoms can include:

• Weakness.
• Cramps.
• Problems with movement.

Ear or eye cells

In the cells of the ears or eyes, mitochondrial diseases can cause:

• Deafness.
• Blindness.
• Droopy eyelids.
• Problems with eye movement.

How are they diagnosed?

If your doctor thinks that you have a mitochondrial disease, your doctor will do a physical examination and medical tests. Your doctor will ask questions about you and your health. You will be asked about your family's health. This is to find out if anyone else in your family has similar symptoms.

The kind of medical tests you get will depend on your symptoms and on which parts of your body are affected. Tests that may be done include a muscle biopsy and imaging tests like an MRI. Your doctor may also want you to have a genetic test.

Your doctor may suggest that you see a genetic counsellor. These counsellors are trained to explain the genetic test and what its results can mean. But you will make the decision about whether to have the test.

How are mitochondrial diseases treated?

Treatment usually focuses on relieving your symptoms and helping you feel better. You and your doctor will work together to find the treatment that works best for you. You may need to see a specialist or a team of specialists.

Treatment may include:

• Getting physiotherapy.
• Eating healthy foods.
• Getting enough rest.
• Avoiding people who are sick.
• Staying at a comfortable temperature.

Your doctor also may suggest taking certain vitamins and supplements.

Your doctor may recommend surgery or other procedures for physical symptoms. These symptoms include drooping eyelids, cataracts, and hearing loss.