What is the cause of mitochondrial myopathy?
Causes. Mitochondrial myopathies may be caused by mutations in the body’s nuclear DNA (the DNA found in the nucleus of cells) or by mutations or deletions in the body’s mitochondrial DNA (mtDNA, the DNA found in cells’ mitochondria).
What causes mtDNA heteroplasmy?
Heteroplasmy describes the situation in which two or more mtDNA variants exist within the same cell. Heteroplasmies are often caused by de novo mutations occurring either in the germline or in the somatic tissues.
What is heteroplasmy and homoplasmy?
When all the mtDNA copies within a cell are identical the state is called homoplasmy. Heteroplasmy is a condition where two or more different variants of mtDNA coexist within a cell.
How common is mitochondrial heteroplasmy?
Mitochondrial heteroplasmy is common in healthy human populations. Before the application of next-generation sequencing (NGS) technologies, most studies focused on the mtDNA control region and revealed that 6∼11.6% of the population carry heteroplasmy in this region (9–11).
What is mtDNA heteroplasmy?
Mitochondrial heteroplasmy represents a dynamically determined co-expression of inherited polymorphisms and somatic pathology in varying ratios within individual mitochondrial DNA (mtDNA) genomes with repetitive patterns of tissue specificity.
What is an example of heteroplasmy?
Generally, individuals with this condition do not experience vision difficulties until they have reached adulthood. Another example is MERRF syndrome (or Myoclonic Epilepsy with Ragged Red Fibers). In MELAS, heteroplasmy explains the variation in severity of the disease among siblings.
How common is heteroplasmy?
Intriguingly, the 10 most common pathogenic mtDNA point mutations were subsequently found to occur in ~1 in 200 healthy individuals, albeit generally at low levels of heteroplasmy31. The techniques used at the time could reliably detect only specific mtDNA alleles and levels of heteroplasmy that were >1%.
What is homoplasmy and heteroplasmy of mitochondria?
Thus a cell can have a mixture of normal and abnormal mitochondrial genomes, which is referred to asheteroplasmy. In contrast,homoplasmy refers a state in which all copies of the mitochondrial genome carry the same sequence variant.