MELAS Syndrome

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Medical Author: William C. Shiel, Jr., MD, FACP, FACR
Medical Editor: Frederick Hecht, M.D., F.A.A.P., F.A.C.M.G.

• What is MELAS?
• What causes MELAS?
• What are the symptoms of MELAS?
• How is MELAS diagnosed?
• When do people with MELAS develop symptoms?
• How is MELAS treated?
• Are there other mitochondrial diseases?

What is MELAS?

MELAS is a rare form of dementia. MELAS is an abbreviation that stands for Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like episodes.

What causes MELAS?

MELAS syndrome is caused by mutations in the genetic material (DNA) in the mitochondria. While most of our DNA is in the chromosomes in the cell nucleus, some of our DNA is in another important structure called the mitochondrion (plural: mitochondria).

The mitochondria are located outside the nucleus in the cell's cytoplasm. Each mitochondrion has a chromosome made of DNA that is quite different from the better known chromosomes in the nucleus. The mitochondrial chromosome is much smaller; it is round (whereas the chromosomes in the nucleus are normally shaped like rods); there are many copies of the mitochondrial chromosome in every cell; and no matter whether we are male or female, we inherit all of our mitochondrial chromosome from our mother.

Much of the DNA in our mitochondria is used to manufacture proteins involved in the key function of mitochondria -- to produce energy and power the cells in our body.

What are the symptoms of MELAS?

As a result of the disturbed function of their cells' mitochondria, patients with MELAS develop brain dysfunction (encephalopathy) with seizures and headaches, as well as muscle disease with a build-up of lactic acid in the blood (a condition called lactic acidosis), temporary local paralysis (stroke-like episodes), and abnormal thinking (dementia).

Suggested Reading by Our Doctors

• Stroke - Learn about strokes symtoms like sudden numbness or weakness in the face, arms, or legs, confusion, vision problems, problems with walking or coordination, or severe headache.
• Dementia - Learn about the types of dementia, and what causes it, the symptoms, diagnosis, treatment and prevention of this progressive disease.
• Seizure (Epilepsy) - Learn about epilepsy, or seizure disorder. Causes include head injury, trauma, prenatal injury, poisoning, medications, stroke, heart attacks, alcoholism, infection, and more. Symptoms, diagnosis, and treatment information is included in the information.

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