Lecture 18 - Testing for Genetic Disorders

Question 1

Prenatal Test Types?

Answer 1

Screening tests - assess risk but not definite, non-invasive low risk; Diagnostic tests - test for specific chromosomal or genetic abnormality, invasive, carries some risk

Question 2

When to test for single gene disorder?

Answer 2

family history, both parents carriers, mother carrier of X linked, one parent has autosomal dominant disorder - SERIOUS DISORDER ONLY

Question 3

When to test for Chromosomal Disorders?

Answer 3

older mother, previous child w significant disorder, exposure to chemical or toxic agent, abnormal screening test result

Question 4

Screening tests?

Answer 4

Ultrasound (nuchal translucency) and maternal serum testing

Question 5

Diagnostic Tests?

Answer 5

Chorionic Villus Sampling, amniocentesis

Question 6

CV sampling?

Answer 6

obtain fetal cells, analyse chromosomes or DNA

Question 7

Amniocentesis?

Answer 7

Done later than CV, collect fluid containing fetal cells

Question 8

Better method of screening?

Answer 8

Detection of cell free fetal DNA in maternal serum

Question 9

Issues to consider?

Answer 9

only testing for common chromosomal disorders, risk of error, small risk to fetus, ethics

Question 10

Benefits of prenatal testing?

Answer 10

reassurance when results normal, psychological preparation for arrival of affected baby, advance warning for medical team, information for termination

Question 11

Counselling components?

Answer 11

care for patients, provides up to date information, non directive