Prenatal diagnosis of genetic diseases

Question 1

Why are prenatal tests carried out?

Answer 1

To test for genetic disorders, and for the benefit of the mother.
Complaication preparation
Termination of affected uterus
Follwoing abnormal finidngs on normal scan

Question 2

When are these tests carried out?

Answer 2

If there is a high risk of ANEUPLOIDY
- Down syndrome test
- Previous aneuploidal foetus
- Maternal request 
OR KNOWN GENETIC DISORDER
- X-linked
- CF

Question 3

What are the types of prenatal screening?

Answer 3

Scanning - ultra, MRI
Non-invasive - Maternal blood test, cffDNA
Invasive - CVS, amniocentesis

Question 4

When are prental tests carried out?

Answer 4

Folllowing abnormal findings after routine scan

Question 5

How do the non-invasive screening methods indicate issues?

Answer 5

Blood test
-Markers indicate risk of trisomy 21 or neural tube defects

cffDNA

• DNA fragments in maternal plasma, 10-20pc is fetal from placenta
• For X-linked disease

Question 6

What are limitations of non-invasive methods?

Answer 6

For multiple pregnancies - unable to tell which DNA is which

Higher BMI women, cffDNA is less prevalent

Question 7

Benefits of non invasive

Answer 7

NO INCREASE RISK OF MISCARRIAGE

LESS DIFFICULT

Question 8

How does CVS indicate if disease

Answer 8

Quicker than amnio

Fetal DNA obtained

11-14 weeks

1-2pc miscarriage

Question 9

Amnio

Answer 9

16 weeks

1pc

amniotic fluid sample

Question 10

What are the repoductive options

Answer 10

conceive naturally

conceive naturally but be tested

adopt

no kids

PGD - IVF w embryo testing

arrange temination

couselling

personal beliefs, previous cearios- take into account