Mitochondrial diseases

Question 1

Mitochondrial DNA

Answer 1

1. 16.5kb
2. DS, circular; some maybe linear
3. 37 genes: 22tRNAs, 2rRNA, 13 subunits of ETC
4. 2-10 copies in each mito
5. Higher mutation rate (fewer repair mechanisms, more exon-dense)

Question 2

Heteroplasmy

Answer 2

1. presence of both normal and abnormal mitochondria within a cell
2. May be highly variable from tissue to tissue

Question 3

Primary mitochondrial diseases

Answer 3

abnormality of a critical mitochondrial protein made from nuclear or mito genome

Question 4

Secondary mitochondrial diseases

Answer 4

secondary to other cellular processes such as infection, medications, physiological stressors

Question 5

When suspected, test…

Answer 5

1. plasma lactate levels (CSF levels too)
2. Ketones, acylcarnitines, urine organic acids
3. Plasma AA (Ala elevations can reflect long-term lactic acidosis)
4. Neuroimaging to determine brain damage
5. Muscle biopsy most accurate: direct measure of oxidative phosphorylation activity and can measure levels of complexes