Leigh's Disease

** The following information was taken directly from a Patient Education Booklet "Understanding and Coping with Mitochondrial Disease, A guide for patients and parents" Authored by Laura Bainbridge, RN, BScN, MEd; Medical Consultant and Editor: Mark Tarnopolsky, MD, PhD FRCP(C) from the Neuromuscular and Neurometabolic Centre of Hamilton Health Sciences, 2007 **

What is Mitochondrial disease?

Mitochondrial disease refers to a group of disorders. Each of these conditions involves a problem with mitochondria.

Mitochondria are tiny structures inside almost every cell in your body; all the way from your skin to the organs inside your body. Their main job is to use the food and oxygen that enter the cells to make energy. Almost all of the energy your body needs for daily life and growth comes from mitochondria. There are so many types of Mitochondria disease it would be impossible to name them all, and many have yet to be discovered. Each condition is the result of a genetic mutation - a specific change in the genetic material of the mitochondrial. The mutation causes the mitochondria to fail.

When mitochondria fail, less and less energy is made in the cells. The cells may stop working or die. Depending on where the affected cells are, parts of the body may not function properly and many health problems can result. The symptoms of Mitochondrial disease can range from mild to severe.

There is no cure for mitochondrial disease. However, many people have a normal life span with their disease well managed.

Leigh's Disease is a type of "Mitochondrial Disease".

What are the signs and symptoms?

Every cell in the body, except red blood cells, contains hundreds to thousands of mitochondria working to make energy. The mitochondria in some areas of the body may be working properly, but not in other areas. This can cause a wide variety of symptoms.

There is no one identifying sign or feature of Mitochondrial disease. Symptoms can vary and range from mild to sever, even among affected family members. In mild cases, young people may learn to cope and adapt to the amount of energy they have and don't realize they have symptoms, or adults may comment that they were healthy as a child, but not really athletic.

People with Mitochondrial disease often have one or more of these symptoms:

developmental delay or regression in development
seizures
migraine headaches or strokes
muscle weakness (may be on and off)
poor muscle tone (hypotonia)
poor balance (ataxia)
painful muscle cramps
unable to keep up with peers (low endurance)
chronic fatigue
stomach problems (vomiting, heartburn, acid reflux, pain)
breathing problems
eyes are not straight (strabismus)
decreased eye movement
loss of vision or blindness
droopy eye lids (ptosis)
loss of hearing or deafness
heart, liver or kidney disease at a young age
parts of body are shaky (tremors)

Although some of these symptoms are common in the general population, people with Mitochondrial disease are usually affected with multiple symptoms at a young age.

How is the diagnosis made?

Mitochondrial disease is difficult to recognize, because there are so many possible symptoms and they can range from mild to severe. There are some physical signs and symptoms (such as developmental delay, seizures, poor muscle tone, acid reflux, vision and hearing loss), which could lead someone to suspect mitochondrial disease.

A diagnosis of Mitochondrial disease may be confirmed with diagnostic tests, which include:

Genetic testing
Muscle biopsy
Magnetic Resonance Imaging and Spectroscopy (MRI and MRS)
Blood tests for lactate and pyruvate
Urine tests for organic acids, which may indicate problems with metabolism present since birth (called inborn errors of metabolism)
Forearm exercise testing
Exercise an muscle strength testing

Other tests may include:

a lumbar puncture (spinal tap) to test and evaluate fluid around the brain and spinal cord
echocardiogram (ECHO) to check if the heart muscle is affected
electroencephalogram (EEG) to check brain activity for seizures
pulmonary function tests (PFT or spirometry) to check how well the lungs are working

How is Mitochondrial disease treated?

Unfortunately, there is still no cure or even a treatment that can guarantee better health or function. The goals of treatment are to ease symptoms, improve function and slow down the progression of the disease.

The effectiveness of treatment varies from person to person, depending on the exact disorder and severity. Generally those with mild disorders tend to respond to treatment better than those with severe disorders. Treatment will not reverse the damage that has already occurred, such as brain malformations or damage from a stroke. The doctor will decide what types of treatment/therapy will best benefit your child's specific disease, based on a complete assessment of their health.

What can we expect in years to come?

This is an important question, but one that is not easy to answer. So much depends on the type of Mitochondrial disease and what parts of the body are affected. We do know that the majority of people with Mitochondrial disease live for years with their disease well managed and their life expectancy unaltered.

We are sad to say that the prognosis for children who are severely affected by Mitochondrial disease is poor. Mutations such as Leigh's disease and Lethal Infantile Mitochondrial Disease (LIMD) are very severe. Children whose hearts are affected at an early age may develop a thickening of the walls of the heart (called cardiomyopathy) which shortens their life.