Genetics of Development Flashcards
regulative phasee
cells are functionally equivalent and loss of a part of embryo can be compensating for by neighboring similiar cells
mosaic phase
a loss of cell cannot be compensated
what are the 3 axes in the embryo
anterior postier
dorsal ventral
left right
what axes is the first visible structure in the embryo
anterior posterio
what does extoderm form
skin and nerovus system
what does mesoderm form
bones, muscle, internal organ
what does endoderm form
cells of gut and leng epithlum
what proteins specify dorsal;/ventral axis
noggin and chordin
what signaling protein causes left right asymmetry
sonic hedgehog
hodal
initated the left looping of the heart tube
situs inverstus
organs are the mirror image of what they are supposed to be
situs ambiguus
orientation of the organs is radmosized
shoulder to fingertep is
proximal distal
thumb to 5th finger is
anterior posterio
dorsum to palm is
dorsal ventral
patterning along the anteior/posterio axis is determined by waht
HOX genes
what do HOX genes contain
DNA binding domain called homeodomain
;what are the 5 mechanisms operating in development
gene regulation by transcription factors and chromatin modifation
cell-cell signalling
development of specific cell shape and polarity
movement and migration of cells
programmedc ell death
malformation
intrinsic abnoramlity in the developmental process -
example of malformation
polydactylyl
deformation
extrinsic influence on teh development of affected tissue
example of deformation
lack of aminiotic fluid puts contstraite on fetus
disruption
destruction of developing tissue
example of disruption
amniotic bands wrap aroun dfetal limbs
isolated anomlaie
affect a single body region (cleft palet)
sequence
cascase of events that leads to multiple malformations
syndrome
affect several body regions and most often display chromosomal or mendelian inherence
a squence is present when
disease phenotypes are caused sequentially by a single defect
a syndrome is present when
all of the disease phenotypes are caused by a single defect simultaneously
how are anomalies classied
stage of development when the defect happened
abnoramlity oxxuring during the first 1-4 weeks of development prodcue what
multiple major abnormalities in entire embryonic regions
abnoramlities occuring from week 5 to week 8 produce waht
affect specific organs and produce single major anomalies
abnoramlies occurring after week 9 affect what
mild effect
major anomaliy
have surgical or cosemntic conseuqnces
mino anomalies
have little impact on well -being of pt
what percentage of children are born with a recognizable birth defect
2-3%
how many infant deaths are caused by prematurity
20%
how comman afer heart defects
1/100 -1/200 live births
how common is pyloric stenosis
1/300
how common is neural tube defect
1/1000
how common is orofacial cleft
1/700 - 1/1000
how common is clubfoot
1/1000
what are teh msot frequenct identifable cuase for birth defect
genetic defect
