Genetics

Question 1

what is a polymorphism

Answer 1

variation in the genome with frequency >1%

Question 2

what is a mutation

Answer 2

gene change causing genetic disorder

Question 3

what are SNPs

Answer 3

single nucleotide polymorphisms

genetically determined differences that usually do not have any effect on phenotype

Question 4

what are CNVs

Answer 4

copy number variations

very prevalent and can be devastating

Question 5

long arm

Answer 5

q

Question 6

short arm

Answer 6

p

Question 7

what is translocation

Answer 7

rearrangement of genetic material between chromosomes

Question 8

is a robersonian translocation balanced or unbalanced

Answer 8

balanced

Question 9

do robertsonian translocations show more phenotype in children than parents

Answer 9

yes

Question 10

risk of robertsonian translocation

Answer 10

miscarriage

Question 11

smaller translocations are more/less likely to cause miscarriage and more/less likely to be damaging

Answer 11

less

more

Question 12

larger translocations are more/less likely to cause miscarriage and more/less likely to be damaging

Answer 12

more

less

Question 13

47XY+21

Answer 13

down’s syndrome

trisomy 21

Question 14

47XY+14

Answer 14

trisomy 14

miscarriage

Question 15

47XY+18

Answer 15

edward syndrome

trisomy 18

Question 16

45X

Answer 16

turner sydrome

Question 17

47XXY

Answer 17

klinefelter syndome

Question 18

what is aneuploidy

Answer 18

whole extra or missing chromosome

Question 19

why is X chromosome aneuploidy better tolerated than others

Answer 19

one is inactivated

Question 20

what is mosaicism

Answer 20

different cells have a different genetic makeup due to point mutation of chromosome abnormality

Question 21

what is an insertion/deletion mutation

Answer 21

base is inserted or deleted into sequence which can cause a frame shift mutation

Question 22

what is a missense mutation

Answer 22

base substituted for another, may reduce protein function

Question 23

what is a nonsense mutation

Answer 23

base substituted for one that codes for a stop codon

Question 24

what is a silent mutation

Answer 24

one that has no effect on protein synthesised

Question 25

what is a triplet expansion mutation

Answer 25

replication of a trinucleotide

Question 26

what is the standard normal comparison

Answer 26

wild type - US caucasian male

Question 27

what is penetrance

Answer 27

likelihood of having the disorder if you have the mutation

Question 28

what is penetrance in mendelian disease

Answer 28

100%

Question 29

what is mendelian disease

Answer 29

disease caused by a single gene

Question 30

Autosomal dominant

Answer 30

50% risk if one parent affected males and females, all generations equally affected if a copy is passed on they will be affected

Question 31

autosomal recessive

Answer 31

2 copies required 25% chance is both parents have the gene more common consanguineous families less generations affected

Question 32

X- linked

Answer 32

more common in males female carriers do not show major features males cannot pass it on 50% males affected, 50% females carriers son cannot get it mutation from dad

Question 33

Mitochondrial

Answer 33

inherited maternally

Question 34

what is imprinting

Answer 34

differences in gene expression depending on whether condition is maternally or paternally inherited

Question 35

what is heteroplasmy

Answer 35

different daughter cells have different number mutant mitochondria, severity dependent on number mitochondria

Question 36

Array CGH

Answer 36

first line | deletions/duplications

Question 37

what is FISH used for

Answer 37

detecting specific part of chromosome and abnormal protein numbers

Question 38

PCR

Answer 38

amplified piece of genome to look for mutations

Question 39

NGS

Answer 39

assess entire genome

Question 40

why are cancer cells heterogenous

Answer 40

they show mosaicism

Question 41

what is a germline mutation

Answer 41

inherited cancer genes

Question 42

what is a somatic mutation

Answer 42

non inherited cancer genes that may be altered due to carcinogens

Question 43

what is a driver mutation

Answer 43

mutations driving carcinogenesis

Question 44

what is a passenger mutation

Answer 44

mutations due to an unstable tumour

Question 45

what is epigenetics

Answer 45

study of changes in gene expression without sequencing change

Question 46

what are the consequences of methylation?

Answer 46

DNA coils around histones tighter so trancription halted | in some cases tumour suppressors are not transcribed

Question 47

what are oncogenes activated by

Answer 47

proto-oncogenes

Question 48

what are proto-oncogenes activated by

Answer 48

point mutations gene amplifications translocations

Question 49

name a point mutation common in melanoma

Answer 49

BRAF

Question 50

name a gene amplification causing breast cancer formation

Answer 50

HER2

Question 51

name a translocation causing CML

Answer 51

Philadelphia chromosome

Question 52

is one copy of a mutated tumour suppressor enough to cause cancer?

Answer 52

no, there must be two

Question 53

tumour suppressor mutations are dominant/recessive

Answer 53

recessive

Question 54

features suggestive of inherited cancers

Answer 54

1st/2nd degree relatives with it early onset bilateral tumours in paired organs