Genetics of Development

Question 1

Regulative phase vs mosaic

Answer 1

Regulative: day 0 - 14: any cell loss will not cause damage

Mosaic: cell loss will result in major damage and cannot be compensated

Question 2

What axis is formed first?

Answer 2

anterior/posterior: defined by the primitive streak; develop 3 germ layers; nodal, a morphigen is imporant for this

Question 3

What does the ectoderm form?

Answer 3

skin and NS

Question 4

What does the mesoderm form?

Answer 4

bone, muscle, internal organs

Question 5

What does the endoderm form?

Answer 5

cells of gut and lung epithelium

Question 6

After the anterior/post axis forms, what are the last 2 axis?

Answer 6

Dorsal/Ventral: noggin/chordin

Left/Right Axis: Shh (from the notochord) promotes left/right asymmetry; nodal causes asymmetric of left side and left-looping of the heart

Question 7

Shoulder-to-fingertip?

Answer 7

proximal-distal

Question 8

Thumb-to-5th finger

Answer 8

anterior to posterior

Question 9

dorsum to palm

Answer 9

dorsal/ventral

Question 10

What is patterning due to?

Answer 10

Patterning along the post/ant axis is due to HOX, a family of transcription factors.

4 HOX clusters on 4 chromosomes

respond in response to morphogens; different ratios correspond to different fate

Question 11

What are the 5 mechanisms operating in development?

Answer 11

1. gene regulation by TFs
2. cell signaling by contact or morphogens
3. development of cell shape/polarity
4. movement and migration of cells
5. programmed cell death

Question 12

What terms give information about the cause of an abnormality?

Answer 12

malformation, deformation, disruption

Question 13

What result from an intrinsic abnormality in the developmental process? (can affect a germline/organ)

Answer 13

malformations

Question 14

What results from an extrinsic influence on the development of the affected tissue (example: oligohydramnios)

Answer 14

deformations

Question 15

What results in the destruction of developing tissue?

Answer 15

disruption

Question 16

What is an isolated anomaly?

Answer 16

sporadic or multifactorial in origin and only affect 1 body region

Question 17

What is a sequence?

Answer 17

single event –> cascade of events –> multiple malformations

Question 18

What is a syndrome?

Answer 18

disease phenotypes caused by a single defect

Question 19

What type of abnormalities occur during weeks 1-4?

Answer 19

blastogenesis: VACTERL

vertebral
anal atresia
cardiac
tracheo-esophagal fistula
renal
radial limb

Question 20

What abnormalities are occurring from week 5 - 8?

Answer 20

organogenesis: organss and congenital heart defets

Question 21

Abnormalities occurring after week 9?

Answer 21

mild effect, such as single palmar crease

Question 22

What are the 5 most common birth defects and their frequencies?

Answer 22

heart defects 1/100-1/200
pyloric stenosis 1/300
neural tube defects 1/1000
orofacial clefts 1/700-1/1000
clubfoot 1/1000

Question 23

What mutation in mice is related to robustness?

Answer 23

formin