Mitochondrial diseases are rare diseases that can pass from mothers to their children. Diseases occur when mitochondria don’t work the way they should.
Mitochondria are tiny parts of cells in the body. Mitochondria call the powerhouse of a cell because one of their jobs is to produce energy.
These diseases can appear at any age. And they can affect many areas of the body.
Examples of these diseases include:
- Kearnes-Sayre syndrome. Symptoms usually appear before age 20 and affect the eyes and ears.
- Leigh’s syndrome. It affects the nervous system of a baby. It usually begins in the first year of life.
- The MERRF syndrome. MERRF affects the nervous system, muscles, and other body areas.
- MELAS syndrome. MELAS affects many body parts, including the brain, nervous system, and muscles.
What are the Symptoms?
Symptoms depend on the type of cells that have damaged mitochondria. Symptoms can vary from person to person.
Mitochondrial disease in brain cells can cause symptoms such as:
- A decrease in intellectual capacity.
- Brain attacks.
When the disease is in muscle cells, symptoms can include:
- Movement problems.
In the cells of the ears or eyes, mitochondrial diseases can cause:
- droopy eyelids
- Problems with eye movement.
The kidneys, nerves, or liver may affect other body parts.
Causes of Mitochondrial Diseases
As mentioned, the common factor among the diseases is the loss of metabolic capacity by the mitochondria of the affected tissues or areas. Metabolism requires hundreds of chemical reactions, and when one or more of the intermediates in these reactions do not work correctly, there is an energy crisis. As a result, the products of incomplete metabolism can accumulate as “poison” in the body.
This “poison” can disrupt other chemical reactions necessary for cell survival, worsening the energy crisis. In addition, these molecules can act as free radicals (reactive substances that by themselves form harmful compounds with other molecules), causing damage to the mitochondria over time.
The severity and spectrum of mitochondrial diseases seem at first glance disproportionate to the minimal amount of mitochondrial DNA in the human genome if we compare it with the amount of DNA present in the cell nucleus (about 0.1% corresponds to Mitochondrial DNA -about 37 genes-, compared to the remaining 99.9% -about 24,000 nuclear genes-). However, this fact is not due to the whim of nature, but there are specific and defined causes that give rise to this fact:
- All mitochondrial DNA is coding, while in nuclear, there are multiple non-coding gene introns.
- There are fewer genetic repair mechanisms for possible mutations or reading errors than in the nucleus.
- The mitochondrion is an organelle with a significant presence of free radicals.
- These last two points cause the mutation rate to be ten times higher than in the nucleus, which explains many genetic diseases of mitochondrial origin.
How are Mitochondrial Diseases Diagnosed?
If you or your doctor reflect you have mitochondrial disease, your doctor will do a physical exam and medical tests. Your doctor will ask you questions about yourself and your health. They will also ask about your family’s health to determine if anyone else in your family has similar symptoms.
Your medical tests will depend on your symptoms and which parts of your body are affected. Tests may include a muscle biopsy and imaging tests such as an MRI. Your doctor may also want you to have a genetic test.
Your doctor may suggest that you see a genetic counsellor. Those counsellors train to explain genetic testing and its results, but you decide whether or not to get tested. They also provide education and support to families with members who have congenital disabilities or genetic conditions such as mitochondrial diseases. So genetic counselling can help you understand your risk of having a child with mitochondrial disease.
How are they Treated?
Treatment usually focuses on relieving symptoms and helping you feel better. You and your doctor will work together to find the best treatment for you. You may need to see a specialist or a team of specialists.
Treatment may include:
- Do physiotherapy.
- Eating healthy food.
- Get plenty of rest.
- Avoid people who are sick.
- Keep at a comfortable temperature.
Your doctor may also mention that you take specific vitamins and supplements. Surgery or other procedures may recommend for physical symptoms such as droopy eyelids, cataracts, or hearing loss.
In the case of patients with mitochondrial disease who do not know the genetic cause, it is customary to recommend annual follow-up appointments since mutations in new genes that cause it constantly discovers.
Also Read: CMT Disease – Symptoms, Diagnosis and More