Neural tube defects

Question 1

What maternal serum marker is elevated in NTD?

Answer 1

Alpha fetoprotein

Question 2

What are the risk factors for neural tube defects?

Answer 2

1) Genetic cause (familial, syndromes with autosomal recessive inheritance, aneuploidy 13, 18, triploidy)

2) Exposure to environmental agents:
- diabetes-hyperglycemia
- hyperthermia (hot tub, sauna, fever)
- medications (valproic acid, carbamazepine, coumadin, thalidomide)

3) Geographical region-ethnicity, diet
- UK
- India
- China
- Egypt
- Mexico

William’s OB

Question 3

What is the recurrence risk of a NTD with a couple who have previously had a child with either anencephaly or spina bifida?

Answer 3

4%

William’s OB

Question 4

What is the recurrence risk of a NTD if one of the parents are affected?

Answer 4

5%

William’s OB

Question 5

What dose of folic acid is recommended for women at higher risk of NTD?

Answer 5

4 mg PO daily pre-conception and during first trimester

Question 6

Where is AFP made?

Answer 6

Synthesized by fetal yolk sac in early gestation then by the GI tract and liver

Question 7

What factors can influence maternal serum AFP level?

Answer 7

1. ) Maternal weight
2. ) Gestational age-maternal serum AFP increases by 15% each week
3. ) Race or ethnicity- African american women at least 10% higher serum AFP
4. ) Diabetes: women with overt diabetes have 3-4 fold increase for NTD but may have 20% lower AFP
5. ) Multifetal gestation-higher screening rate