Extra definitions

Question 1

What is the name of a gene that does not tolerate one copy?

Answer 1

haploinsufficient

Question 2

Where is the major site of methylation?

Answer 2

cytosine residues within the CG dinucleotide

Question 3

What is the name of a female who must be a carrier for an X-linked recessive condition?

Answer 3

obligate carrier

Question 4

What is micro satellite instability?

Answer 4

a hallmark of impaired DNA mismatch repair

it gives phenotypic evidence that MMR is not working properly

Question 5

What structure includes long stretches of the repeated sequence TTAGGG?

Answer 5

telomere

Question 6

What are the pseudoautosomal regions PAR1 and PAR2?

Answer 6

short regions of homology between the X and Y chromosomes

Question 7

Which enzyme shows genetic variation in activity that can cause toxicity on treatment with some cytotoxic drugs?

Answer 7

thiopurine methytransferase (TPMT)

Question 8

What is lyonization?

Answer 8

a process by which one of the copies of the X chromosome is inactivated in some females

it is packaged in such a way that it has a transcriptionally inactive structure called heterochromatin

Question 9

Genetic deficiency of which enzyme is associated with failure to recover from anaesthesia?

Answer 9

butyrylcholinesterase

Question 10

What is meant by epigenetics?

Answer 10

DNA modifications that do not affect the nucleotide sequence but can affect gene activity