Mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes: A distinctive clinical syndrome

Abstract

We report on two patients who have a mitochondrial myopathy, encephalopathy, lactic acidosis, and recurrent cerebral insults that resemble strokes (MELAS). These two and nine other reported patients share the following features: ragged red fibers evident on muscle biopsy, normal early development, short stature, seizures, and hemiparesis, hemianopia, or cortical blindness. Lactic acidemia is a common finding. We believe that MELAS represents a distinctive syndrome and that it can be differentiated from two other clinical disorders that also are associated with mitochondrial myopathy and cerebral disease: Kearns-Sayre syndrome and the myoclonus epilepsy ragged red fiber syndrome. Existing information suggests that MELAS is transmitted by maternal inheritance. The ragged red fibers suggest an abnormality of the electron transport system, but the precise biochemical disorders in these three clinical syndromes remain to be elucidated.

Extensive and rapid screening for major mitochondrial DNA point mutations in patients with hereditary hearing loss

“…[9][10][11][12] In contrast, the m.3243A4G mutation causes several major clinical phenotypes of mitochondrial disease such as myopathy, encephalopathy, lactic acidosis, stroke-like episodes, maternally inherited diabetes and deafness, chronic progressive external ophthalmoplegia and mitochondrial diabetes. [31][32][33] However, epidemiological evidence of the prevalence of the patients with the m.3243A4G mutation in the population still has limitations. The patients with m.3243A4G including asymptomatic cases in the general population are thought to be as common as 6.57-16.3 per 100 000.…”

The other, forgotten genome: mitochondrial DNA and mental disorders

“…[44][45][46] The reason for this is unclear and may reflect mitochondrial inheritance or differences in opportunity between the sexes for finding partners. 47 Comorbidity with mitochondrial disease Patients with MELAS sometimes demonstrate delusions and hallucinations due to delirium [48][49][50][51] or schizophrenialike symptoms. [52][53][54][55][56][57][58][59] Of these, delusions and hallucinations due to delirium [48][49][50][51] can be regarded as directly related to neuronal dysfunction due to MELAS.…”

Mitochondrial Genetics

“…Patients commonly manifest with generalized tonic-clonic seizures, recurrent headaches, anorexia with recurrent vomiting and postlingual hearing loss, [78][79][80] but can manifest with impaired: motor ability, vision and mental acuity due to the cumulative effect of multiple stroke-like episodes. MELAS is commonly (80% of cases) caused by a A>G transition at m.3243 in MTTL1, 81 but is also associated with variants in MTND5.…”