Disorders/screening (P1)

Question 1

Cystic fibrosis

Answer 1

Disorder of cell membrane
Production of mucus
Shortened life span
affects digestive system
Affects fertility
Managed with medication

Question 2

Polydactyl

Answer 2

Growth of fingers/toes

Question 3

Amniocentesis

Answer 3

Ultra sound imaging is used to detect the position of the foetus
A needle is inserted through the wall of the uterus and a sample of the amniotic fluid is taken
Cells within the fluid are genetically screened to determine the presence of “faulty” genes

Question 4

Amniocentesis effects

Answer 4

Risk of miscarriage (0.5-1%)
Greater if performed before 15 weeks
Risk of damage to placenta or baby 
Infection (0.1%)
Risk of club foot
Blood sensitation of the baby if the mother is RhD+

Question 5

Chorionic Villus Sampling (CVS)

Answer 5

Only carried out if there is serious risk for genetic abnormalities
Can be carried out trans-abdomically (needle inserted through the abdominal wall)
Can be carried out trans-cervically (tube/forceps through cervix in vagina
Samples of chronic villi taken from the placenta
Cells are genetically screened to detect “faulty genes”

Question 6

CVS disadvantages

Answer 6

Risk of miscarriage 0.5-1% in first 23 weeks
Risk of incorrect cells being sampled (1%)
Risk of severe infection (0.1%)
Blood sensitisation of baby if mother is RhD+
Abdominal pain for 2-3 days after

Question 7

Non-invasive prenatal testing (NIPT)

Answer 7

A blood sample is taken from the mother
Detects fragments of free DNA from the foetus
Can reliably detect sex of the foetus as well as a number of genetic disorders
A positive result is followed by CVS or amniocentesis to confirm

Question 8

NIPT disadvantages/advantages

Answer 8

Requires a maternal blood test
Can detect some genetic disorders from 10 weeks
No risk to foetus