Mitochondrial Inheritance

Question 1

Mitochondrial DNA is passed from the _____ to _____.

Answer 1

mother; all of her children

Question 1

Mitochondrial diseases are disorders caused by _____.

Answer 1

dysfunction of the respiratory chain

Question 2

What is the mutation in Kearns-Sayre?

Answer 2

a large deletion of mtDNA (~12 genes)

Question 2

What are the signs and symptoms of MELAS?

Answer 2

muscle weakness, seizures, repetitive stroke-like episodes, elevated lactic acidosis

Question 4

replicative segregation

Answer 4

multiple copies of mtDNA are randomly sorted among new mitochondria

Question 4

What is the incidence rate of MERRF? New mutation rate?

Answer 4

1:400,000; very low

Question 5

What does MELAS stand for?

Answer 5

mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes

Question 6

What are the signs and symptoms of MERRF?

Answer 6

weakness, myotonia, seizures, ataxia, dementia, ragged-red muscle fibers

Question 6

What is the incidence rate of Leber Hereditary Optic Neuropathy?

Answer 6

1:30,000

Question 7

threshold effect

Answer 7

too much mutated mitochondrial DNA in a cell- problems start presenting

Question 8

What is mutated in MERRF?

Answer 8

MT-TK gene

Question 9

What is MERRF?

Answer 9

myoclonic epilepsy with ragged-red fibers

Question 11

What are the clinical manifestations of Kearns-Sayre?

Answer 11

eye problems, cardiac conduction effects, ataxia, deafness, kidney problems

Question 13

What are 4 mitochondrial diseases?

Answer 13

1) Kearns-Sayre 2) MELAS 3) MERRF 4) Leber Hereditary Optic Neuropathy

Question 15

Mitochondrial DNA encodes ____ genes.

Answer 15

37

Question 15

What is the mutated gene in Leber Hereditary Optic Neuropathy?

Answer 15

several mitochondrial genes

Question 17

What is the MELAS mutation?

Answer 17

several different genes with same manifestation; usually MT-TL1

Question 18

What is the incidence rate of Kearns-Sayre?

Answer 18

1:100,000

Question 19

What is the incidence rate of MELAS? What is the new mutation rate?

Answer 19

1:300,000; very low

Question 20

ataxia

Answer 20

abnormal gait

Question 21

heteroplasmy

Answer 21

receiving both some mutated and some normal mitochondria

Question 22

What are the signs and symptoms of Leber Hereditary Optic Neuropathy?

Answer 22

vision loss

Question 23

Why does Leber Hereditary Optic Neuropathy show reduced penetrance?

Answer 23

50% of males get vision loss, but only 15% of females do