What is Mitochondrial Disease?

Mitochondrial Disease is a complex disease and therefore difficult to explain in words alone.
The Lily Foundation have created a bespoke educational animation to explain how vital Mitochondria are to sustain life, and also what happens when they go wrong.

Please share this video to educate and raise awareness of Mitochondrial Disease.


What are Mitochondria? 

In every cell in the body, Mitochondria are responsible for producing energy (called ATP) that the cell needs to function. Cells make up tissues and organs in our bodies, for example the heart and liver.

They are like power stations in our bodies, supplying the energy every cell needs to function.

If our cells do not have energy, then the tissues or body organs that the cells are made up of do not work properly, in the same way that if power stations do not produce enough energy for the country there will be areas of blackout, where parts of the country cannot function.

Inside the Mitochondria

Inside the Mitochondria a reaction takes place that changes the food energy we have broken down into a different form of energy that the cell can use.

There are a number of complex chemical changes that need to happen to produce ATP (energy).

To change (or convert) the food energy we need special proteins to help called enzymes.  Enzymes help to make the chemical reactions faster. There are many different enzymes in each Mitochondrion.

Each cell has mitochondria in it to supply energy. The number of mitochondria in each cell can vary between one and hundreds, depending on how much energy that cell needs. A busy cell such as a brain or liver cell needs a lot of energy to function properly therefore has a lot of mitochondria.

Just as in any reaction to produce energy, a “fuel” must be combined with oxygen. This happens within the part of the mitochondria called the Respiratory Chain (also called the Electron Transport Chain).

There are five parts to this Chain, called complexes, which are numbered I (one) to V (five), with roman numerals. To produce energy the reaction needs to pass through each part of this chain, which sits inside of the membrane (outer covering) of the mitochondria.

What is Mitochondrial Disease?

When a person has Mitochondrial Disease the Mitochondria in the cells are not producing enough energy for the cell. Sometimes they do not work at all, and sometimes they are just not very efficient.

If a cell does not get enough energy (ATP) it cannot function properly.

There is a huge variety in the symptoms and severity of Mitochondrial Disease. It depends on how many cells are affected, and where they are in the body.

Every person with Mitochondrial Disease is affected differently.  Each individual affected will have a different combination of Mitochondria that are working and not working within each cell.

However, there are times when particular body systems are affected in a recognisable pattern and these have particular names, for example Alpers, Leigh’s disease, MELAS and MERRF. The commonest parts of the body affected are those that have the highest energy demands; brain, muscle, liver, heart and kidney.

If a lot of Mitochondria in the body are affected in the important body organs, like the brain, Mitochondrial disease can be very serious.

The symptoms of Mitochondrial disease are usually progressive in body systems where the cells have a high demand for energy, such as brain cells.

Why has it taken so long to diagnose it?

Mitochondrial disease is very rare. Symptoms of the disease can begin at any age. It can take a long time to get a diagnosis because a variety of different body systems are usually affected, in a way that is not linked. One of the characteristics of Mitochondrial disease is that it involves seemingly unrelated body organs. We look for other organ systems to see if they are affected, even if there are no symptoms.

For a diagnosis, we usually take a piece of tissue (biopsy) and examine the chemicals within it. This is usually either a muscle or liver biopsy.

The chemicals we are looking for can take a long time to find, and results are usually not available for at least six weeks after the biopsy has been taken.

Sometimes even if the test is “negative”, it does not rule-out the diagnosis. It may be that the piece of tissue examined did not contain the faulty mitochondria as the areas affected tend to be patchy. In these cases we usually rely on looking at all the symptoms and what is the most likely diagnosis.

Can we treat it?

Unfortunately there is no cure for Mitochondrial disease at present.

Treatment is usually supportive to relieve the symptoms demonstrated, for example treating seizures with medication.

We also try to make the respiratory chain more efficient by using a co-factors and vitamins. Examples of these are Ubiquinone (Co-factor Q10), Thiamine and Riboflavin.

Some people find that using a special diet can help, and this varies depending on which part of the respiratory chain is affected. However, this should only be tried with guidance from your Metabolic team.

Any metabolic stress on the body, for example an illness, has the potential to cause a worsening or progression of Mitochondrial Disease, as the cells may not be able to cope with the extra demand placed upon them.

It is difficult to live in a world where all potential metabolic stresses are removed, but it is important to be aware, so that early medical advice and treatment of any illness can be started.

How do you get it?

Mitochondria are different to other cell structures, as they have their own DNA.  DNA is the inherited “blueprint” that contains the necessary instructions required to build the Mitochondria. If there is a fault in this programme, the mitochondria will not function properly.

Mitochondrial disease can be inherited, but the way this can happen is extremely complicated. It can be from the mother or father or both, or the mistake in the faulty gene may have arisen for the first time in the affected person.

All of this should be discussed with a genetics counsellor, as each case is different.

Symptoms of the disease can be unmasked by an unrelated illness, a cough, cold or diarrhoea and vomiting. However the person affected has always had the condition, rather than having “caught” it from someone else.

For more detailed information a useful website is: The Children's Mitochondrial Disease Network