Genetics of Development Flashcards
Regulative phase vs mosaic
Regulative: day 0 - 14: any cell loss will not cause damage
Mosaic: cell loss will result in major damage and cannot be compensated
What axis is formed first?
anterior/posterior: defined by the primitive streak; develop 3 germ layers; nodal, a morphigen is imporant for this
What does the ectoderm form?
skin and NS
What does the mesoderm form?
bone, muscle, internal organs
What does the endoderm form?
cells of gut and lung epithelium
After the anterior/post axis forms, what are the last 2 axis?
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
Shoulder-to-fingertip?
proximal-distal
Thumb-to-5th finger
anterior to posterior
dorsum to palm
dorsal/ventral
What is patterning due to?
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
What are the 5 mechanisms operating in development?
- gene regulation by TFs
- cell signaling by contact or morphogens
- development of cell shape/polarity
- movement and migration of cells
- programmed cell death
What terms give information about the cause of an abnormality?
malformation, deformation, disruption
What result from an intrinsic abnormality in the developmental process? (can affect a germline/organ)
malformations
What results from an extrinsic influence on the development of the affected tissue (example: oligohydramnios)
deformations
What results in the destruction of developing tissue?
disruption
What is an isolated anomaly?
sporadic or multifactorial in origin and only affect 1 body region
What is a sequence?
single event –> cascade of events –> multiple malformations
What is a syndrome?
disease phenotypes caused by a single defect
What type of abnormalities occur during weeks 1-4?
blastogenesis: VACTERL
vertebral anal atresia cardiac tracheo-esophagal fistula renal radial limb
What abnormalities are occurring from week 5 - 8?
organogenesis: organss and congenital heart defets
Abnormalities occurring after week 9?
mild effect, such as single palmar crease
What are the 5 most common birth defects and their frequencies?
heart defects 1/100-1/200 pyloric stenosis 1/300 neural tube defects 1/1000 orofacial clefts 1/700-1/1000 clubfoot 1/1000
What mutation in mice is related to robustness?
formin
