Genetics and foetal medicine

Question 1

What conditions are routinely screened for at 8 weeks

Answer 1

Trisomy 13 - Patau’s syndrome
Trisomy 18 - Edward’s syndrome
Trisomy 21 - Down’s syndrome

Question 2

What is involved in NIPT

Answer 2

Analysis of placental DNA in maternal serum

Question 3

What increases chance of an inadequate NIPT sample

Answer 3

Increased BMI

Question 4

What tests can be performed on high risk trisomy patients on NIPT

Answer 4

Chorionic villous sampling
Amniocentesis

Question 5

When can CVS be performed

Answer 5

11-14 weeks

Question 6

When can amniocentesis be performed?

Answer 6

> 15 weeks

Question 7

What is a possible setback of CVS

Answer 7

not always diagnostic as in cases of mosaicism, sampling the placenta may miss a mutation in the foetus, and in some cases, the placenta may contain the mutation while the foetus does not

CVS should therefore be done in combination with scans and amniocentesis should be offered if they do not compare

Question 8

What DNA testing should be performed:

Cleft palate or Cardiac abnormalities but no mutations on NIPT

Answer 8

Foetal chromosomal microarray for smaller changes

Question 9

Stages of prenatal NGS

Answer 9

1. Consent both parents
2. Wet sequencing analysis
3. Data analysis - Known genes (2000+), de-novo variants, recessive variants, variant effects
4. Lab-clinician MDT
5. Clinician reads report
6. Clinician sees patients

Question 10

What is used to induce TOP in babies >24 weeks

Answer 10

Intra-cardiac potassium chloride