L4.2: Mitochondrial conditions

—> tissues with high energy demand (brain, muscles, heart, neurons, GI; …)

a) mtDNA -> mostly maternal inheritance (sperm’s mitochondria = destroyed shortly after fertilization)

& no effective repair mechanism in mtDNA

b) nuclear DNA -> autosomal inheritance

• no introns (only 3 non-coding regions) / procaryotic origin

• own genetic code for translation

• no effective DNA repair mechanism (10x higher mutation rate)

• no recombination

• mutations can affect phenotype

• mutations can confer a replication advantage

• chronic progressive external ophthalmoplegia (CPEO)

  • bilateral ptosis

  • progressive inability to move the eyes and eyebrows

  • restircted eye movement in all directions

  • assymmetric ptosis and strabism

• CPEO plus = CPEO + additional symptoms (muscular hypotonia, cardiac insufficiency, …)

• LHON (leber hereditary optic neuropathy)