About: MERRF syndrome is a research topic. Over the lifetime, 204 publications have been published within this topic receiving 17351 citations. The topic is also known as: Fukuhara syndrome (disorder) & Myoclonic epilepsy - ragged red fibers (disorder).
TL;DR: This finding demonstrated that a nucleotide change in a mitochondrial DNA energy production gene can result in a neurological disease.
Abstract: Leber's hereditary optic neuropathy is a maternally inherited disease resulting in optic nerve degeneration and cardiac dysrhythmia. A mitochondrial DNA replacement mutation was identified that correlated with this disease in multiple families. This mutation converted a highly conserved arginine to a histidine at codon 340 in the NADH dehydrogenase subunit 4 gene and eliminated an Sfa NI site, thus providing a simple diagnostic test. This finding demonstrated that a nucleotide change in a mitochondrial DNA energy production gene can result in a neurological disease.
TL;DR: An A-to-G transition mutation at nucleotide pair 3,243 in the dihydrouridine loop of mitochondrial tRNALeu(UUR) that is specific to patients with MELAS is reported, which creates an Apal restriction site and could perform a simple molecular diagnostic test for the disease.
Abstract: MITOCHONDRIAL encephalomyopathies are usually divided into three distinct clinical subgroups: (1) mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS); (2) myoclonus epilepsy associated with ragged-red fibres (MERRF); and (3) chronic progressive external ophthalmoplegia (CPEO) including Kearns-Sayre syndrome1–5. Large deletions of human mitochondrial DNA and a transition mutation at the mitochondrial transfer RNAlys gene give rise to CPEO including Kearns–Sayre syndrome6–8 and MERRF9,10, respectively. Here we report an A-to-G transition mutation at nucleotide pair 3,243 in the dihydrouridine loop of mitochondrial tRNALeu(UUR) that is specific to patients with MELAS. Because this mutation creates an Apal restriction site, we could perform a simple molecular diagnostic test for the disease. The mutation was present in 26 out of 31 independent MELAS patients and 1 out of 29 CPEO patients, but absent in the 5 MERRF and 50 controls tested. Southern blot analysis confirmed that the mutant DNA always coexists with the wild-type DNA (heteroplasmy).
TL;DR: Observations demonstrate that mtDNA heteroplasmy can occur in man and that human disease may be associated with defects of the mitochondrial genome.
Abstract: In vitro studies of muscle mitochondrial metabolism in patients with mitochondrial myopathy have identified a variety of functional defects of the mitochondrial respiratory chain, predominantly affecting complex I (NADH-CoQ reductase) or complex III (ubiquinol-cytochrome c reductase) in adult cases. These two enzymes consist of approximately 36 subunits, eight of which are encoded by mitochondrial DNA (mtDNA). The increased incidence of maternal, as opposed to paternal, transmission in familial mitochondrial myopathy suggests that these disorders may be caused by mutations of mtDNA. Multiple restriction endonuclease analysis of leukocyte mtDNA from patients with the disease, and their relatives, showed no differences in cleavage patterns between affected and unaffected individuals in any single maternal line. When muscle mtDNA was studied, nine of 25 patients were found to have two populations of muscle mtDNA, one of which had deletions of up to 7 kilobases in length. These observations demonstrate that mtDNA heteroplasmy can occur in man and that human disease may be associated with defects of the mitochondrial genome.
TL;DR: An A to G transition mutation at nucleotide pair 8344 in human mitochondrial DNA has been identified as the cause of MERRF, providing molecular confirmation that some forms of epilepsy are the result of deficiencies in mitochondrial energy production.
TL;DR: An association of dyssynergia cerebellaris myoclonica associated with Friedreich's ataxia and mitochondrial myopathy in 2 patients is unlikely to be coincidental but may represent one nosological entity.