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Genetic and Rare Diseases Information Center (GARD)

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Mitochondrial encephalomyopathy lactic acidosis and stroke-like episodes

Other Names for this Disease
  • MELAS syndrome
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How is mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) inherited?

MELAS is caused by mutations in mitochondrial DNA (mtDNA) and is therefore transmitted by maternal inheritance (also called mitochondrial inheritance).[1] This type of inheritance applies to all conditions caused by genes in mtDNA. Mitochondria are structures in each cell that turn molecules into energy, and each contain a small amount of DNA. Only egg cells (not sperm cells) contribute mitochondria to offspring, so only females can pass on mitochondrial mutations to their children.[2] Conditions resulting from mutations in mtDNA can appear in every generation of a family and can affect both males and females. In most cases, people with MELAS inherit an altered mitochondrial gene from their mother. Less commonly, the condition results from a new mutation in a mitochondrial gene and occurs in an individual with no history of MELAS in the family.[2]
Last updated: 12/4/2013

  1. Salvatore DiMauro and Michio Hirano. MELAS. GeneReviews. November 21, 2013; Accessed 12/4/2013.
  2. Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes. Genetics Home Reference. November 2006; Accessed 12/4/2013.