MELAS Syndrome

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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).

Medically Reviewed by a Doctor on 12/12/2013

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