MELAS

MELAS is a mitochondrial disorder marked by mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes. It is commonly caused by mitochondrial DNA mutations, especially m.3243A>G.

m.3243A>G: A mitochondrial DNA variant in MT-TL1, commonly associated with MELAS and other mitochondrial phenotypes. This is the mutation most often associated with MELAS.
Mitochondrial DNA: The genetic material found in mitochondria, inherited almost exclusively from the mother in humans. Most MELAS cases arise from variants in this genome.
Magnetic resonance imaging: An imaging method that uses magnetic fields and radio waves to produce detailed images of the body. MRI helps characterize lesions during MELAS stroke-like episodes.
MERRF: A mitochondrial disorder characterized by myoclonus, epilepsy, and ragged-red muscle fibers. MERRF is another mtDNA disease, but myoclonus and myopathy define its typical presentation.
Mitochondrial heteroplasmy: The coexistence of different mitochondrial DNA sequences within a cell or individual. Different mutant loads help explain why MELAS severity varies among tissues and people.
Maternal inheritance: Transmission of genetic material from a mother to her offspring. Mitochondrial DNA variants causing MELAS are generally passed through the maternal line.
Magnetic resonance spectroscopy: An MRI technique that estimates concentrations of selected chemicals in tissue. It can reveal elevated lactate in affected brain regions.
Leigh syndrome: A progressive neurological disorder caused by defects in mitochondrial energy metabolism. Its characteristic progressive brain lesions differ from MELAS stroke-like episodes.
Oxidative phosphorylation: The mitochondrial process that uses electron transport to generate most cellular ATP. Impaired energy production is central to MELAS pathophysiology.
MT-TL1: A mitochondrial gene encoding the transfer RNA for leucine at the UUR codons. The common m.3243A>G variant lies in this gene.

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