Mitochondrial Genetics*

Question 1

mtDNA stats

Answer 1

16.6 kb, 37 genes (13 proteins, 22 tRNAs, 2 rRNAs), 1 kb control region

Question 2

what are the 4 principles of maternal inheritance

Answer 2

asexual, heteroplasmy, bottleneck and threshold

Question 3

2 examples of heteroplasmic primary mtDNA mutation

Answer 3

1. kearns-sayre syndrome. The single most common cause is heteroplasmy for the 4.9 kb mtDNA “common deletion.”
2. MELAS mitochondrial myopathy encephalopathy lactic acidosis and stroke like

Question 4

an example of homoplasmic primary mtDNA mutation

Answer 4

LHON leber hereditary optic neuropathy. most common mtDNA disorder

Question 5

an example of disorders due to mutations in nuclear genes, whereas the protein is imported into mitochondria

Answer 5

Friedreich Ataxia
caused by GAA repeat
insufficient frataxin (maintenance of iron chaperone)

Question 6

Mitochondrial disorders that can be caused either by mutations in mtDNA or in nuclear genes

Answer 6

Leigh Syndrome

(progressive neurodegeneration in basal ganglia, cerebellum and brain stem

Question 7

Mitochondrial disorders due to mutations in nuclear genes, resulting in mtDNA instability and secondary mtDNA mutations

Answer 7

Progressive External Ophthalmoplegia (PEO)

and Gamma Polymerase (POLG)