Mitochondria are located in the cells that produce the energy required by the body. Mitochondrial diseases occur as the result of defects in mitochondria that can cause muscular conditions known as mitochondrial myopathies and when it affects the brain, it is called mitochondrial encephalomyopathies. In most of the cases, the mitochondrial disease is a multisystem disorder that causes a problem with more than a single type of cell, tissue or the organ. The muscles and the nerve cells of the body require high amounts of energy and hence this condition often presents the muscular and neurological problems.
Causes
Mitochondrial diseases are inherited as the result of a defective gene which in most cases is passed from the parents. Individuals normally inherit two pairs of genes from their parents and genetic conditions can occur when a defective gene is inherited from the parents. The inheritance pattern of mitochondrial disease is possible in an autosomal recessive trait, autosomal dominant manner or as a mitochondrial inheritance. Autosomal recessive form of inheritance occurs when the affected individual receives a single copy of the mutated gene from each parent. Autosomal dominant pattern means the child receives a single copy of the defective gene from either parent. The mitochondrial inheritance is exclusively inherited from the mothers which are the defect occurring in the mitochondrial DNA.
Symptoms
The symptoms of mitochondrial myopathy include muscle fatigue and exercise intolerance. The muscle weakness is commonly evident in the muscles that control movements of the eyelid and the eyes. As the consequence, the progressive external ophthlmoplegia occur which is the paralysis of the eye movements and a condition called ptosis that is the drooping of the eyelids. Ptosis can affect the normal vision of the affected individual which can be corrected by surgery. Mitochondrial myopathies can also cause muscle weakness in other parts of the body such as the face, neck, and the limbs which can present problems with swallowing and slurred speech. Exercise intolerance is the fatigue caused by physical exertion with varying severity among the affected cases.
Diagnosis
The diagnosis is based on the assessment of the individual’s medical history, physical and neurological examinations. The diagnostic tests can consist of tests of strength and endurance such as exercise test and to evaluate the individual’s vision, speech and basic cognitive skills. A muscle biopsy may be required which will be examined under the microscope to identify abnormalities. Other specialized tests can include CT scan, EEG to monitor the brain wave activity and ECG to monitor the heart’s activity and blood tests to assess the function of the liver and the kidney. The genetic testing can also help identify the mutation that is performed on muscle DNA.
Treatment
There isn’t any curative medication available for the mitochondrial myopathies. The treatment focuses on providing supportive medications that can modify some of the symptoms of this condition. The treatment consists of nutritional supplements based on three natural substances that are essential for the energy production in the cells. This includes creatine, carnitine and coenzyme Q10 which are often combined together for the treatment of the mitochondrial disease.
References
http://muscle.ca/wp-content/uploads/2012/11/FS_Mitochondrial_Myopathy_eng.pdf
https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Mitochondrial-Myopathy-Fact-Sheet#What causes mitochondrial myopathies?
http://www.musculardystrophyuk.org/app/uploads/2015/02/Mitochondrial-myopathies-2015.pdf
