Abstract
m.3243A>G MT-TL1 mutation is the most common mitochondrial DNA mutation that results in a wide spectrum of disorders in a maternally inherited pedigree. In adult patients, many present with symptoms and signs indistinguishable from acquired diseases and the correct diagnosis is often delayed after many years. Nevertheless, clues suggesting m.3243A>G usually exist early in the disease course but are only realized late. These hints, from the evolution of symptoms and signs, family background, investigation results, or a combination of these, enable the physician to make the correct diagnosis early, which is important for appropriate treatment and better patient care. As with other inheritable diseases, genetic counselling should be offered regarding the disease management, inheritance mode, recurrence risk, usefulness and limitations of genetic testing and reproductive options.
Highlights
Mitochondrial diseases are considered a category of “rare diseases”, with a population prevalence of 1 in 5000 based on epidemiological studies [1] [2]
Recent studies suggested insulin resistance and relative insulin deficiency is the main reason for maternally inherited diabetes and deafness (MIDD), the insulin secretion from pancreatic β-cell is dependent on mitochondrial function [20] [21]
Our own experience in intravenous L-arginine is not encouraging, and we believe that discrepancy is because of treatment delay, since the study patients were treated within one hour of symptoms onset, but none of our patient was treated within 24 hours
Summary
Mitochondrial diseases are considered a category of “rare diseases”, with a population prevalence of 1 in 5000 based on epidemiological studies [1] [2]. The A>G transition of the mitochondrially encoded tRNA leucine 1 (UUA/G) gene at position 3243 (m.3243A>G, MT-TL1) is the most common mutation in human mitochondrial diseases [3] This mutation accounts for most of the severe childhood neurological phenotype mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), and maternally inherited diabetes and deafness (MIDD) in adults [4] [5]. These two discrete phenotypes are only part of the disease spectrum, many patients carrying this mutation do not fall into either group [6]. We share our experience in the clinical management of adult patients with this m.3243A>G mutation through a descriptive analysis to highlight the heterogeneity and diversity of the disease nature, and the treatment related issues
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