Genetics

Question 1

What is meant by a ‘synonymous mutation’?

Answer 1

Substitution of one base (e.g leucine substituted for another leucine) means that the amino acid sequence is not changed

Question 2

What is the mechanism of ivecaftor and which condition is it used for?

Answer 2

Ivecaftor is used in CF as an ion channel opener

Question 3

A couple wish to conceive. The mother does not have cystic fibrosis but her sister does. The father has no relevant FH. What is the chance of their child being affected?

Answer 3

Dad has a 1 in 25 chance of being a carrier (population risk)

Mum has a 2 in 3 chance of being a carrier (she might carry the gene on one chromosome or the other or neither - she obviously doesn’t have both copies or she would be affected)

Childs risk = 2/3 times 1/25 times 1/4

= 1/150

Question 4

What is the first step in the central dogma of making a protein from a gene?

Answer 4

Transcription

Question 5

Why advantage does next generation sequencing have over sanger (conventional) sequencing?

Answer 5

It allows sequencing of a much larger number of genes

Question 6

Why is Array Comparative Genomic Hybridisation (aCGH) preferable to karyotyping as a first test for chromosome analysis?

Answer 6

It has higher resolution

Question 7

What characteristic of a cancer cel is central to allowing it to acquire further new characteristics?

Answer 7

Genomic instability

Question 8

Which ethical principle is most important in genetic counselling for a patient who may have Huntington Disease?

Answer 8

Patient autonomy

the patient decides whether or not they want to know