Mitochondrial Disease: Diagnosis and Prognosis

All cells in the human body, except red blood cells, contain mitochondria. These are specialized parts of the cells that convert food and oxygen into energy. When there is a problem with these cells, there is a breakdown in the systems in the body which can lead to a whole host of symptoms ranging from mild to severe.

Most mitochondrial disease is inherited from the mother. Mitochondria contain their own DNA. All of this DNA is inherited from the mother. As the mitochondria replicate, defects increase. The rate of increase affects the age of onset and the severity of the disease. The location of the affected mitochondria affects which systems of the body are involved and what symptoms will be present. Mitochondrial disease can also be caused by mitochondrial toxins and by random mutations of the mitochondrial DNA.

The symptoms of mitochondrial disease are diverse, depending on the systems affected, making diagnosis difficult. Symptoms may include seizures, severe unexplained vomiting, heat or cold intolerance, poor muscle tone, developmental delays, severe unexplained diarrhea or constipation, poor growth, visual or hearing problems, and the inability to fight off infections. Heart, liver, kidney, or respiratory disorders may be caused by mitochondrial disease as well as diabetes and thyroid conditions. To facilitate diagnosis, doctors look for patterns in symptoms. A child or adult with three or more diseased organ systems or with a typical disease following an atypical pattern may have mitochondrial disease. Accurate diagnosis requires a battery of tests. Those with mild mitochondrial disease may go undiagnosed until adulthood or even until after death.

The prognosis for those with mitochondrial disease varies depending on the organ systems involved. The muscles, nerves, and cerebrum require the most energy and are therefore the most severely affected by damaged mitochondria. Several syndromes caused by mitochondrial disease have been recognized. Your doctor can work with you to find out if your symptoms fall within the boundaries of one of these syndromes giving you a better idea of how your individual disease may progress. The worst cases result in death. In very mild cases, the only problems may be exercise intolerance, or the necessity to watch what and how one eats. In some cases, the disease involves hearing or vision loss, or the necessity of increased medical care for minor illnesses like colds.

One in 4000 children will be diagnosed with mitochondrial disease before the age of 10. Adults are increasingly being diagnosed with mitochondrial disease also. Many conditions including type 2 diabetes, Parkinson's disease, and Alzheimer's disease can damage mitochondria. Some medications can also cause harm.

Mitochondrial disease is not curable. Treatment options to help with symptoms and to slow the spread of the disease are available. Early diagnosis improves the prognosis of those affected. Treatments include various drugs and vitamin supplements as well as occupational and physical therapy. Mitochondrial function and disease is increasingly a subject of medical research with some doctors now specializing in mitochondrial medicine.