Mitochondrial Myopathies

Question 1

Leber’s hereditary optic neuropathy

Answer 1

Single base change
Complex I
Mitochondria partially defective in electron transport from NADH to ubiquinone
Causes blindness

Question 2

Myoclonus epilepsy with ragged red fibres

Answer 2

Point mutation
tRNA (lysine)
Disrupts synthesis of proteins essential for OXPHOS
Skeletal muscle fibres have abnormally shaped mitochondria - clump together

Question 3

Mitochondrial encephalomyopathy

Answer 3

Affects brain and skeletal muscle

Symptoms present in childhood

Question 4

Kearns-Sayre Syndrome

Answer 4

5kb deletion
Onset before age 20
Dementia and retinitis pigmentosa

Question 5

Diagnosis

Answer 5

Biochemical tests
Histology
Genetic Testing

Question 6

Treatment

Answer 6

Occupational/physical therapy
Vitamin therapies
No specific treatment

Question 7

Prevention

Answer 7

IVF strategy to replace defective mitochondria
Merge DNA from 2 eggs - one from mother one from healthy donor with functioning mitochondria
Mitochondria Gene Replacement (pronuclear stage)
Maternal Spindle Transfer (alternative)