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Sunday, 14 August 2005
Sunday, 14 August 2005
Mitochondrial Encephalomyopathy, Lactic Acidosis, and Strokelike Episodes; Myopathy, Mitochondrial-E


MELAS stands for mitochondrial Myopathy, Encephalopathy, Lactic Acidosis, and Stroke-like episodes, which are the four main features of this disease. MELAS is a relatively rare genetic disorder caused by a genetic change (mutation) in the DNA found in mitochondria. Mitochondria are the part of cells responsible for the generation of energy needed for the body. Mitochondria are found in nearly all cells of the body, so when they do not function correctly there are wide-ranging effects on many parts of the body.


Exactly how often MELAS occurs is not known. Males and females are both equally affected by this disorder, as are members of all ethnic groups. The age when signs and symptoms usually start varies, but most individuals first notice symptoms between the ages of 4 and 20 years of age. Occasionally, symptoms can be seen in children as young as 4 months of age.

Signs and Symptoms

Although the symptoms of MELAS vary, the four symptoms that make up the syndrome’s name are most common. Therefore, it is common for individuals with MELAS to have or develop:

  • mitochondrial myopathy (muscle dysfunction due to malfunctioning mitochondria) encephalopathy (effects on the brain)
  • lactic acidosis (the buildup of acid in the body due to poor energy production by the mitochondria)
  • stroke-like symptoms Symptoms may also include any or all of the following:
  • exercise intolerance (muscles getting tired unusually fast when exercising)
  • weakness in the arms and legs
  • short stature
  • hearing loss
  • learning disabilities
  • balance problems
  • development of diabetes mellitus
  • heart disease

Possible Causes

Over 80% of all known cases of MELAS are due to a single genetic change in the mitochondrial DNA (mtDNA). Having this mutation, however, does not necessarily mean that an individual will develop MELAS and other genetic changes are known to cause this syndrome. Mitochondria are passed from mother to child in the egg, so MELAS is inherited from the mother and all of her children are at risk of developing this disorder.


The diagnosis of MELAS is made if three criteria are met: 1) the individual has had a stroke before the age of 40; 2) he/she has some type of encephalopathy (seizures, dementia, or both); and 3) the individual has lactic acidosis or ragged-red fibers (abnormal muscle cells that can be seen on a muscle biopsy). Recurrent headaches, exercise intolerance, recurrent nausea, and/or any of the other symptoms mentioned above also aid in the diagnosis. DNA testing may also be done to see if one of the known genetic mutations that cause MELAS is present.


No cure is available for individuals with MELAS at this time. Most treatments are aimed at minimizing symptoms including preventing seizures with the aid of antiepileptic medications, improving muscle strength with physical therapy, and treating endocrine disorders such as diabetes mellitus and hypoparathyroidism with appropriate medications and diet. Individuals with MELAS are usually cared for by a team of physicians including a neurologist, a geneticist, an endocrinologist, a nephrologist, a cardiologist, and an ophthalmologist.


The symptoms of MELAS vary a great deal but in most patients symptoms slowly progress and patients’ health progressively declines. Since the disease is due to the body’s inability to produce energy properly, anything that requires the body to expend more energy will lead to a flare-up of symptoms. The problems with the brain often progress to dementia (loss of brain function) and heart abnormalities can lead to heart failure or other serious heart problems. Seizures can become frequent and harmful to the patient, as well. As a result of a loss of muscle mass and general wasting caused by the disease, a significant number of individuals with MELAS die by the age of 20.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks MELAS Syndrome
This website has some basic, easy-to-understand information about MELAS as well as a good number of helpful weblinks with further information about the disease. MELAS
This website is a database for all federally- and privately-funded research. As of July 2005, there was one study of MELAS currently enrolling patient volunteers.

Google Search for MELAS

References and Sources

Scaglia F (2004). eMedicine: MELAS Syndrome. Hirano M, et al (1992). MELAS: An original case and clinical criteria for diagnosis, Neuromuscular Disorders, 2(2), p 125-35.