Teratogens / Early Fetal Development (HOX, etc.)

Question 0

What 6 drugs are Cat. X?

Answer 0

1. Methotrexate
2. Warfarin (use heparin)
3. Statins
4. Isoretinoic acid
5. DES
6. Thalidomide

Question 1

Which 3 antibiotic classes are potentially teratogenic?

Answer 1

1. Fluoroquinolones (tendon weakness, malformation)
2. Aminoglycosides (hearing loss)
3. Tetracyclines (discovered teeth)

Question 2

When is 4 chambered heart seen?

Answer 2

4 weeks

Question 3

When does fetal movement begin?

Answer 3

8 weeks

Eight, gait

Question 4

When does ext genitalia resemble the sex of fetus?

Answer 4

10 weeks

TEN, PENis

Question 6

When do limb buds begin to form?

Answer 6

4 weeks

4 weeks, 4 limbs

Question 7

What side teratogenic effect do the anti-epilectic drugs carbamazepine and valproic acid have?

Answer 7

Neural tube defects–> if can’t stop the med before pregnancy, begin folate supplements months prior to pregnancy

Question 8

What abnormality can lithum cause to a fetus?

Answer 8

Ebstein malformation–> a type of cardiac defect

Question 9

What 2 drugs can increase the risk of spontaneous abortion?

Answer 9

1. Isoretinoic acid

2. Warfarin (give heparin to anti-coagulate instead)

Question 10

What two drugs can cause limb hypoplasia in an infant?

Answer 10

1. Cyclophosphamide (alkylating agent)

2. Thalidomide

Question 11

Mutation in what HOX gene can cause synpolydactyly?

Answer 11

HOXD-13 (extra digits and are fused together)

Question 12

Which gene is responsible for correct Anterior - posterior (cranial/caudal) organization during development?

Answer 12

Sonic hedgehog gene

*produced at base of limbs in Zone of Polarizing Activity

Question 13

What gene is responsible for appropriate dorsal/ventral organization of body during development?

Answer 13

Wnt-7 gene

*produced at apical ectodermal ridge (thickened ectoderm at distal end of each developing limb)

Question 14

What gene is responsible for the elongation of limbs?

Answer 14

FGF gene (stimulates mitosis of underlying mesoderm)

*defects in FGF3 receptor = achondroplasia

Question 15

What is the function of HOX genes in general?

Answer 15

Involved in segmental organization of embryo in a cranial caudal fashion; mutations may result in appendages in the wrong locations

Question 16

By what week do all three germ layers exist in the embryo?

Answer 16

Week 3; 3 = trilaminar disc

*gastrulation is the process that forms this trilaminar disc; starts with the epiblast invaginating to form the primitive streak

Question 17

Wat embyronic structure secretes Hcg?

Answer 17

Syncytiotrophoblast (within week 1)

Question 18

How do gestational and developmental age differ?

Answer 18

Gestational age is usually about two weeks less than developmental age, because it starts after the last missed period; usually about two weeks after the embryo has begun developing.