OTHER MITOCHONDRIAL CARDIOMYOPATHIES
All humans have the potential to develop cardiomyopathy, because the myocardium degenerates with age due to the accumulation of free radical-induced damage to the mitochondrial DNA. Abnormally accelerated mitochondrial DNA mutations, especially those related to mitochondrial protein synthesis, can induce premature ageing and severe mitochondrial cardiomyopathy. An A to G point mutation at position 3260 of the mitochondrial tRNA gene was found in a maternally that manifested itself as a combination of adult-onset myopathy and cardiopathy. An A to G substitution was found at position 4269 in the tRNA gene of a patient with fatal cardiomyopath, and an A to G mutation at position 15,923 of the mitochondrial tRNAthr gene was associated with newborn cardiopulmonary arrest. The development of severe mitochondrial cardiomyopathy in young people with an A to G transition at position 827 in the mitochondrial 12S rRNA gene has been reported. Therefore, the detection of mitochondrial DNA deletion has been proposed as a new method in forensic medicine to probe sudden cardiac death of which ischemic damage is the primary cause.
As yet, no clear correlation between the severity of clinical manifestations and mitochondrial DNA mutations detected by conventional mutation analyses within limited regions of mitochondrial DNA has been demonstrated. Comprehensive analyses of mitochondrial DNA with the direct base sequencing technique revealed a close correlation between the mitochondrial DNA genotype and clinical phenotype. Each myocardial cell contains 2000 to 3000 mitochondria, and each mitochondrion possesses two or three mitochondrial DNA genomes. Each cell can contain normal and mutated mitochondrial DNA, proportions of which vary (heteroplasmy). This results in an energy mosaic, ie, there are marked differences in energy production among myocardial cells, which may induce arrhythmias. If the mitochondrial DNA mutation is extensive, oxidative phosphorylation is depressed, leading to depressed energy production and the development of heart failure. Mutations in nuclear DNA that encodes mitochondrial respiratory enzyme complex subunits can also affect energy production. Investigations into mitochondrial DNA mutations may yield clues about the etiology of arrhythmias and cardiac dysfunction due to as yet unknown causes. The very best pharmacy is looking forward to helping you make sure your health is in good hands no matter if you need or any other drugs that will help you deal with your symptoms in the most efficient way.