Genetics

Question 1

how can fetal tissue be accessed

Answer 1

placental - chorionic villus biopsy
skin/urine cells - amniocentesis
blood - fetal blood sampling

Question 2

when can CVS be done

Answer 2

after 11. 5 weeks

Question 3

when can amniocentesis be done

Answer 3

after 15 weeks

Question 4

when can fetal blood sampling be done

Answer 4

after 18 weeks 2 pecent miscarriage risk

Question 5

when can fetal dnA from maternal blood be sample

Answer 5

after 8 weeks

Question 6

what is the disadvantage of CVS

Answer 6

you may have confined placental mosiciasm

Question 7

Which tests analyse the whole genome

Answer 7

Karyotypte
Array CGH
Quantification of fetal DNA in maternal serum
Whole genome sequencing

Question 8

at what stage of the the cell cycle is karyotyping done

Answer 8

metaphase

Question 9

What tests look for targeted problems

Answer 9

point mutation testing
FISH
Quantitative fluorescent PCR

Question 10

What kind of problem will array not show

Answer 10

balanced translocation

Question 11

what is a polymorphism

Answer 11

genetic variation that is not disease causing per-se

Question 12

what is a copy number variation

Answer 12

insertions or deletions of DNA segments - a type of polymorphism

Question 13

what is a single nucleotide polymorphism

Answer 13

single base changes

Question 14

when is fish used

Answer 14

when missing bit of chromosome is too small to see on karyotype - when you know what part you are looking at

Question 15

when is QF-PCR used

Answer 15

when you know what chromosomes you want to specifically look at

Question 16

when would you do array or chromosome analysis in a fetus

Answer 16

high risk of trisomy
fetal abnormality on scan
balance chromosomal rearrangement

Question 17

what type of IUGR would worry you towards a genetic mutation

Answer 17

SYMMETRICAL

Question 18

what can fetal dna in maternal circulation be used to find

Answer 18

sex determination
trisomy testin

occasionally picks up chromosome or single gene deletions

only 10 percent of the dna sampled is fetus - harder to see mutations

Question 19

Why is aCGH the best genetic test in looking for downs etc

Answer 19

will detect small deletions

Question 20

why is sex chromososne aneuploidy better tolerated eg XXX, xxy

Answer 20

x inactivation

Question 21

what are the features of turners

Answer 21

webbed neck and oedema

Question 22

what features occur in patau

Answer 22

bilateral ceft lip
postaxial polydactyly
can have cyclopia

Question 23

what is a robertsonian translocation

Answer 23

two acrocentric chromosomes stuck end to end

Question 24

what do robertsonian translocations increase the risk of

Answer 24

trisomy

Question 25

what is aneuploidy

Answer 25

too many chromosomes

too few chromosomes

Question 26

when is array used

Answer 26

deletions/duplications

Question 27

when is chromosome analysis used

Answer 27

when you think it is a big mutation

Question 28

when is next generation sequency

Answer 28

for very very small mutations down to 1 base pair

Question 29

when can cardiac defects be seen on a scan

Answer 29

12-20 weeks

Question 30

when can microcephaly and short limbs be seen on a scan

Answer 30

usually not until after 22 weeks