prenatal screening

Question 1

what is the difference between screening and testing

Answer 1

screening is offered to all pregnant women and gives a statistical risk of disability

testing is only given to some women and is diagnostic

Question 2

what are the purposes of screening and testing

Answer 2

to reassure parents
to inform and prepare parents 
allows early treatment 
allows termination 
provides information which allows choice

Question 3

what types of testing and screening are available

Answer 3

natural conception- non invasive, ultrasound, serum. invasive: chorionic villus sampling and amniocentesis

IVF: preimplantation genetic diagnosis

Question 4

what is the ethical issue with ultrasound

Answer 4

parents not forced to have it therefore doctors can’t be prepared if there are abnormalities

Question 5

when is ultrasound carried out

Answer 5

dating scan at 8-14 wks

anomaly scan at 18-20 weeks

Question 6

what is the down’s syndrome screen

Answer 6

ultrasound and serum test
11 weeks - 14 wks
measures the chance of DS, not diagnostic

Question 7

what is the risk of amniocentesis

Answer 7

risk of miscarriage

club foot if too early

Question 8

how does chorionic villus sampling happen

Answer 8

– Fine needle inserted through abdomen and into uterus; or through
cervix, & small piece of developing placenta removed

Question 9

what is amniocentesis

Answer 9

Needle inserted through the abdomen and into amniotic fluid

Question 10

what diseases can be DNA tested

Answer 10

• Cystic fibrosis
• Phenylketonuria
• Tay-Sachs
• Duchenne Muscular dystrophy
• Huntington’s disease
• Inherited breast & ovarian cancers

Question 11

what are the features of PGD

Answer 11

one cell is removed from embryo
only offered to those at higher risk
expensive but may be cheaper in the long run

Question 12

how serious is serious?

Answer 12

factors to consider are: 
– Take into consider the views of those seeking
treatment
– Likely degree of suffering
– Availability of effective treatment
– Speed of degeneration
– Extent of intellectual impairment
– Social support available
– Family circumstances

think about achondroplasia - is it a disability? how do you define disability?

Question 13

what are the features of huntingtons

Answer 13

autosomal dominant
late onset
degenerative disease

Question 14

what are the issues of prenatal testing for Huntington’s disease

Answer 14

do so on the understanding that parents will terminate if positive
as testing is only available to adults and not all chose to take the tests, so parents will know something the adult doesn’t

Question 15

what are the laws about saviour siblings

Answer 15

initially was only for cord blood and the embryo had to have a risk of inheriting the same condition

now these conditions have been removed

Question 16

what are the ethical issues of saviour siblings

Answer 16

are the sibling’s being used?
what is the psychological effect and the effect on the relationships
what are the impacts of not allowing a saviour sibling
possibility of exploitation

Question 17

what is CRISPR

Answer 17

allows you to edit the embryo’s genes

using enzymes to cut

Question 18

what are the features of BRCA1 gene

Answer 18

breast cancer:80%
ovarian cancer:65%
increased chance of prostate cancer and can pass on

Question 19

what are the features of the BRCA2 gene

Answer 19

breast: 88%
ovarian:37%
increased chance of prostate cancer and male breast cancer
and can pass genes on

Question 20

what are the indications for amniocentesis

Answer 20

previous pregnancy with problems
family history
over 35
antenatal screen suggests problem

Question 21

what does CVS test for

Answer 21

Inherited disorders- CF, sickle cell, thalassemia, muscular dystrophy, chromosomal disorders

Question 22

what should be considered when deciding if a test should become part of a screening programme

Answer 22

predictive power and accuracy
benefits of information
psychological impact
therapeutic possibilities
social and economic factors
resource cost and priority

Question 23

what is tissue typing

Answer 23

using PGD to find an embryo that will be a match for a sick sibling

Question 24

what are the differences between CVS and amniocentesis

Answer 24

amniocentesis happens about a month after CVS

CVS does not detect neural tube defects and has a greater chance of miscarriage

both are diagnostic, both can find out about baby’s chromosomes