Mitochondrial disorders are a group of complex and heterogeneous diseases that may be caused by molecular defects in mitochondrial genomes. Pathogenic mitochondrial DNA (mtDNA) mutations are usually present in the heteroplasmic form. The degree of mtDNA mutation heteroplasmy varies among different tissues. Thus, it is important to detect and quantify the degree of mutation heteroplasmy of mtDNA...

itochondrial cardiomyopathy is one of the main features in patients with mitochondrial diseases caused by mitochondrial DNA (mtDNA) mutations, and it determines the prognosis, as well as encephalopathy.1–3 In particular, an A-to-G transition mutation at nucleotide position 3243 (A3243G) in mtDNA, which was originally discovered in patients with mitochondrial myopathy, encephalopathy, lactic aci...

Eight carriers of the A3243G mutation of mitochondrial DNA without stroke-like episodes were monitored for up to 7 years in clinical and metabolic studies, by magnetic resonance imaging (MRI) and positron emission tomography (PET). None developed mitochondrial encephalopathy (MELAS), but 2 developed diabetes mellitus, 1 terminal kidney failure and 2 cardiomyopathy. One patient improved markedly...

Mitochondrial myopathy, Encephalopathy, Lactic Acidosis, and Stroke-like episodes (MELAS) is a rare mitochondrial disorder. Diagnostic criteria for MELAS include typical manifestations of the disease: stroke-like episodes, encephalopathy, evidence of mitochondrial dysfunction (laboratorial or histological) and known mitochondrial DNA gene mutations. Clinical features of MELAS are not necessaril...

Maternally inherited diabetes and deafness (MIDD), also called mitochondrial diabetes mellitus, is a rare form of diabetes that comprises 0.5-2.8% of the diabetic population. Most cases of MIDD are associated with a point mutation in the mitochondrial DNA (mtDNA) at position 3243 of the leucine tRNA gene (A3243G) . Patients with MIDD are characterized by 1) young onset of diabetes, 2) absence o...

Objective: The aim of the study was to analyze a series of Brazilian patients suffering from MELAS. Method: Ten patients with MELAS were studied with correlation between clinical findings, laboratorial data, electrophysiology, histochemical and molecular features. Results: Blood lactate was increased in eight patients. Brain image studies revealed a stroke-like pattern in all patients. Muscle b...