Genetics

Question 1

What must you inform a patient of prior to genetic testing?

Answer 1

• Why do it
• Odds of a +ve result
• What happens if it’s +ve or -ve
• Risk of False results
• Implications for family members
• DNA stored

Question 2

What way’s can we do genetic testing in obstetrics?

Answer 2

• Tests at birth
• Chorionic villus sampling
• Amniocentesis
• Pre-implantation Genetic Diagnosis
• Non-invasive prenatal diagnosis/testing

Question 3

List some major conditions we can do genetic screening for in babies?

Answer 3

• CF (1 in 2000)
• Sickle Cell
• Phenylketonuria (1in 10,000)
• Congenital Hypothyroidism (1 in 4000)
• Medium Chain Acyl-CoAdehydrogenase Deficiency (1 in 10,000)

Question 4

How do we screen for CF?

Answer 4

• Immunoreactive Trypsine
• Sweat Test
• Genotyping

Question 5

How do we check for PKU?

Answer 5

Biochemical screen (not a genetic test so carriers not identifiable)

Question 6

What happens in PKU?

Answer 6

Unable to break down phenylalanine –> Mental disability

Question 7

How do we manage PKU?

Answer 7

Start a strictly controlled diet by 21 days

Question 8

How can we test for congenital Hypothyroidism?

Answer 8

Hormone test (so again carriers aren’t identified)

Question 9

What happens in CHT?

Answer 9

Not enough thyroxine –> Physical & mental disability

Question 10

How do we manage CHT?

Answer 10

Thyroxine tablets by day 21

Question 11

How is MCADD inherited?

Answer 11

Recessive

Question 12

What happens in MCADD?

Answer 12

Can’t break down fat
-> metabolic crisis if not enough nutrient input

Generally first present at 14months

Question 13

How do we manage MCADD?

Answer 13

Avoid fasting
Monitor frequency of meals

In emergency –> Glucose Polymer and IV dextrose