2.7

Question 1

When does an embryo become a foetus?

Answer 1

At 10 weeks of pregnancy, or 8 weeks after conception

Question 2

What are the 3 methods for testing embryos?

Answer 2

Amniocentesis
Chorionic villus sampling
Non-inasive pre-natal diagnosis

Question 3

What is amniocentesis and how does it work?

Answer 3

A way of obtaining cells from a developing fetus. A developing fetus is wrapped in a membrane called the amnion. The space between the amnion and the fetus is filled with a fluid called amniotic fluid. Amniotic fluid contains some fetal cells. These cells can be examined and their chromosomes observed or the DNA that they contain may be investigated.

Question 4

What is CVS and how does it work?

Answer 4

Procedure in which a small sample of placental tissue (which includes cells of the fetus) is removed between 8 and 12 weeks of pregnancy and tested for genetic abnormalities.

Question 5

What is NIPD and how does it work?

Answer 5

Works by analysing DNA fragments in the mother’s blood plasma during preganancy. Samples are collected after 7-9 weeks of pregnancy. No risk of miscarriage.

Question 6

What is PIGD?

Answer 6

Pre-implantation genetic diagnosis. Embryo is sampled before the transfer to the uterus (8-16 cell stage). Not done routinely as IVF is expensive, stressful and success rates are quite low.

Question 7

What are the implications associated with genetic testing?

Answer 7

Miscarriage
False negative
Abortion - controversial, decision is difficult
Cost
Ethics
Reducing variation over time - ‘designer babies’?