Mitochondrial myopathies Flashcards
Describe mitochondrial DNA
The circular double-stranded molecule, 16.5 kb,
5-10 copies of the genome in each mitochondrion.
mitochondrial DNA is maternally inherited (from the egg)
mitochondrial genome
many of the genes needed for mitochondrial function have moved from the MTN to the nuclear genome however the mt genomes codes for,
12 of the resp chain proteins, 2 rRNA and 22 tRNA
What is ROS and what is the main producer
Resp chain is the main producer of reactive oxygen species, the MTN genome suffers the greatest exposure to, and damage by, ROS.
What are MTN myopathies and name some examples
neuromuscular diseases mostly occurring before the age of 20,
LHON- Leber’s hereditary optic neuropathy
MERRF- myoclonus epilepsy with ragged red fibre.
MELAS- mitochondrial encephalomyopathy
KSS- Kearns-Sayre syndrome
LHON syndrome
single base change in the polypeptide of complex 1, there is partially defective electron transport from NADH to ubiquinone.
MERF Syndrome
A point mutation in the mt gene and disrupts proteins essential for oxidative phosphorylation.
MELAS syndrome
Mt myopathy affecting primarily the brain and skeletal muscle, symptoms appear in childhood including the build of lactic acid, stroke-like episodes of muscle weakness, loss of vision and movement difficulties.
KSS
results from 5kb deletion of the mt genomes, onset before age of 20, short stature and often have multiple endocrinopathies including diabetes, symptoms include dementia and retinitis pigmentosa
How are Mt myopathies treated
diagnose via a combo of biochemical tests, histology and genetic testing
prognosis: variable and dependant on the type of disease
occupational/ physical therapy may extend the range of muscle movement along with vitamin therapies to improve function
How can Mt myopathies be prevented
IVF strategy designed to replace defective mitochondria inherited from a mother.
