Mitochondrial diseases range in severity from almost not diagnosable to fatal. They also range in cause from inherited to acquired mutations (although acquired mutations that cause disease are very rare). A certain mutation can cause several different diseases depending on the severity of the problem in the mitochondria and the tissue the affected mitochondria are in. Conversely, several different mutations may present themselves as the same disease. This almost patient-specific characterization of mitochondrial diseases makes them very hard to accurately diagnose and trace. Some diseases are observable at or even before birth (most causing death) while others do not show themselves until late adulthood. This is because the number of mutant versus wildtype mitochondria varies from cell to cell and tissue to tissue, and is always changing. Because cells have multiple mitochondria, different mitochondria in the same cell can have different variations of the mtDNA genome. This condition is referred to as heteroplasmy. When a certain tissue reaches a certain ration of mutant versus wildtype mitochondria, a disease will present itself. The ration varies from person to person and tissue to tissue (depending on its specific energy, oxygen, and metabolism requirements, and the effects of the specific mutation). Mitochondrial diseases are very numerous and different. Apart from diseases definitely caused by abnormalities in mitochondrial DNA, many diseases are suspected to be caused in part by dysfunction of mitochondria, such as diabetes mellitus, forms of cancer and cardiovascular disease, lactic acidosis, specific forms of myopathy, osteoporosis, Alzheimer's disease, Parkinsons's disease, stroke, and many more. Furthermore, mtDNA mutations are believed to play a role in the aging process.
Tuesday, June 3, 2008
Mitochondrial diseases I
Mitochondrial diseases range in severity from almost not diagnosable to fatal. They also range in cause from inherited to acquired mutations (although acquired mutations that cause disease are very rare). A certain mutation can cause several different diseases depending on the severity of the problem in the mitochondria and the tissue the affected mitochondria are in. Conversely, several different mutations may present themselves as the same disease. This almost patient-specific characterization of mitochondrial diseases makes them very hard to accurately diagnose and trace. Some diseases are observable at or even before birth (most causing death) while others do not show themselves until late adulthood. This is because the number of mutant versus wildtype mitochondria varies from cell to cell and tissue to tissue, and is always changing. Because cells have multiple mitochondria, different mitochondria in the same cell can have different variations of the mtDNA genome. This condition is referred to as heteroplasmy. When a certain tissue reaches a certain ration of mutant versus wildtype mitochondria, a disease will present itself. The ration varies from person to person and tissue to tissue (depending on its specific energy, oxygen, and metabolism requirements, and the effects of the specific mutation). Mitochondrial diseases are very numerous and different. Apart from diseases definitely caused by abnormalities in mitochondrial DNA, many diseases are suspected to be caused in part by dysfunction of mitochondria, such as diabetes mellitus, forms of cancer and cardiovascular disease, lactic acidosis, specific forms of myopathy, osteoporosis, Alzheimer's disease, Parkinsons's disease, stroke, and many more. Furthermore, mtDNA mutations are believed to play a role in the aging process.
