Lecture 18-Prenatal Genetics

Question 0

What is better for detecting NTDs? Ultrasonography or maternal serum AFP (MSAFP)?

Answer 0

ultrasonography

Question 1

Does having a child with a de novo chromosomal abnormality mean that the next child should be tested for one even if the parents didn’t pass it on to the first child?

Answer 1

yes, there is a risk of recurrence of 1/100

Question 2

High AF-AFP is seen in what conditions (4)?

Answer 2

• NTD (highly sensitive)
• fetal blood contamination
• fetal abnormalities (ex: omphalocele)
• placental disorders

Question 3

What is the most important tool for prenatal diagnosis of major anomalies?

Answer 3

ultrasonography

Question 4

What is the strongest indicator of whether or not a parent will decide to undergo diagnostic testing depending on screening tests?

Answer 4

• attitude of the patient

Question 5

What are the patient “types” and describe each.

Answer 5

• Type A: high anxiety, wants tests regardless of risk
• Type B: weighs risks and wants assessment of risk before considering invasive diagnostic testing (best candidate for screening tests)
• Type C: refuses prenatal diagnosis or screening tests

Question 6

Risk based on maternal age can be modified using what screening methods? (2)

Answer 6

• ultrasound

- maternal serum

Question 7

What is the problem with doing screening for mendelian disorders based on ethnicity?

Answer 7

ethnicity is not clear cut–many people don’t even know their ancestry

Question 8

What are the 3 main adjectives to describe fragile X?

Answer 8

• loss of function
• mental retardation
• autism

Question 9

What are 2 major causes of MR?

Answer 9

• aneuploidies

- Fragile X