X-Linked Disorders and Mitochondrial Inheritence

Question 1

What are the key features of X-linked recessive inheritance?

Answer 1

Affects mostly males
All daughters of affected males are carriers
Carrier females have a 50% chance of passing it on to their offspring

Question 2

What is mitochondrial DNA?

Answer 2

Double stranded circular DNA inherited maternally
37 genes
Mutation rate is 5-10x that of nuclear DNA
Does not have histones to repair

Question 3

How can mitochondrial DNA mutations cause disease?

Answer 3

It causes deficiency in the respiratory chain which leads to issues in the production of ATP/apoptosis/reactive oxygen species production
This affects tissues which have high energy requirements (brain/muscles)

Question 4

What is the difference between direct and indirect mutation analysis?

Answer 4

Direct- analyse DNA from affected patient and try and find mutational cause
Indirect- if mutation is not known, use SNPs/linkage markers to track abnormal gene in the family

Question 5

What some problems with indirect analysis?

Answer 5

Non-paternity
Need several family members
Need an informative marker gene

Question 6

What is the gene responsible for hemochromatosis?

Answer 6

Locus heterogeneity

HFE gene mutations usually but can also be others