2 Flashcards Preview

MCD Genetics COPY > 2 > Flashcards

Flashcards in 2 Deck (9)
Loading flashcards...

Give an example of an autosomal recessive disease and the mechanism of action

Cystic Fibrosis – caused by a mutation in the CFTR gene on Chr 7, which affects chloride ion function in epithelial cells. Gives rise to thick mucus.


State two different types of point mutations

Non-sense, mis-sense or silent


State two types of frame shift mutations.



Give an example of an autosomal dominant disease and the mechanism of action.

Huntingdon’s Disease – mutations in the HTT gene on Chr 4, which codes for huntingtin. Mutation leads to production of a toxic protein that accumulates and forms clumps in organs. Causes cell death in the basal ganglia in the brain. It is caused by an unstable CAG repeat – the more repeats you have the more likely you are to get HD. Severity increases with time and age of onset decreases.


State the differences between monogenic and complex diseases.

Monogenic diseases are rare, have a clear inheritance pattern and are not affected by environmental factors Complex diseases are the opposite


Give an example of a mutation in the same gene causing two different conditions

Congenital absence of the vas deferens – caused by mutations in CFTR. Other disease is cystic fibrosis.


State the difference between mutations and polymorphisms.

Mutations are any changes in genetic material that are hereditary Polymorphisms are mutations which occur at >1% frequency in the population


Give an example of a X-linked recessive condition

Haemophilia A and B – A is caused by a mutation in the F8 gene on Chr X which encodes factor VIII.
B – caused by mutation in F9 gene which encodes factor IX


What are the general molecular mechanisms of the different types of genetic disease (autosomal dominant, autosomal recessive, co-dominant)?

Dominant – toxic product produced (treatment aims to neutralise toxic product)
Recessive – absence of functional protein (treatment aims to regain function)