T2L14 Genetic Screening and gene therapy

Question 1

What is genetic screening

Answer 1

Testing for changes in the sequence or structure of DNA to confirm/rule out genetic conditions

Question 2

Name 5 types of screening

Answer 2

Amniocentesis
Carrier screening
In vitro screening
Non-invasive pre natal diagnosis
Chorionic villus sampling

Question 3

Describe the use of carrier testing

Answer 3

Carrier testing is usually offered to people with a family history but anyone can pay for it.

Blood/cheek cells are taken
A DNA probe is inserted into the cells

Radio tracers are used to test for the specific genes

Each DNA probe tests for one type of disorder
Only a small number have been developed

The expected carrier is tested first and if they don’t carry it no further testing is required

Question 4

Describe the use of in vitro/ pre-implantation testing

Answer 4

After IVF (only)
Single cell is removed from the embryo at 8 cells development
The cell is tested for the presence of genetic disorders

The embryo can then be implanted if the outtcome is desired

IVF without this testing ahs the same success rate as with the testing included

Question 5

Describe the use of chorionic villus sampling

Answer 5

Pre-natal diagnosis

Transcervical or Transabdominal needle

Take sample of placental tissue

8-12 weeks gestation (no need for amniotic fluid)

estimated 1-2% miscarriage risk but limited research: higher risk than amniocentesis

Question 6

Describe the use of amniocentesis

Answer 6

Needle inserted into ammniotic fluid to collect fetal cells that have fallen off of the placenta and fetus

15-17 weeks

1% risk miscarriage

Question 7

Describe the use of NIPD

Answer 7

Blood is taken from the mother

10-20% of cell free DNA in the mother’s blood will come from the embryo

This is detectable after 4-5wks with samples collected at 8-9

DNA taken is then analysed

Not invasive/ no miscarriage risk however only tests for limited disorders

Question 8

Name the 4 ethical frameworks and give examples

Answer 8

Rights+Duties: e.g religious teachings, conventions, animal testing

Maximising the amount of good in the world: Good vs Harm, Circumstances

Making decisions for yourself - informed consent

Leading a virtuous life: