Congenital Malformations Flashcards
What 2 factors cause congenital malformations
Genetics and environment
Give 2 examples of how environment can cause malformation
Drugs - acne treatments have RA which affects the midbrain development
Diabetes
What 3 reasons do we study malformation
1- identify cause and understand
2- predict future occurrences (genetic counselling)
3- prevention of them developing treatment
What 2 histological techniques are used in the anatomical approach to what the malformations are
1- gross morphology : dissection to see the organs in detail
2- histology : cut slices into dehydrated cell tissues of embryo and see tissues closely
What is used in histology
Paraffin wax
What are 3 ways we can manipulate the embryo to see what causes malformations
Removal of a specific part eg the node
Replacing a part with another
Drug interference
What is the genetic approach to studying malformations and how is it useful
Gets genetic info by studying families with malformations
Can see which tissues are affected by specific genes
Shows where genes are active (temporal and spacial info)
What 4 techniques does genetic approach use to study malformations / map gene expression
Visualisation of gene expression
Measuring gene expression
Disruption of gene functions: knockout or conditional gene modification
Ectopic gene use- adding extra genes to see the effect (transgenesis or knockins)
What 3 ways can you detect gene expression and analyse it
In situ hybridisation- shows where mrna is located
Immunohistochemistry - shows where protein is expressed
Linking a gene to a transgenesis gene - shows where gene is expressed
Why is single cell (isolation from embryo) rna sequencing important
It is used to map all the genes and when in development it’s expressed
What 2 ways can knockout mice be produced and show which one is faster and successful
Using embryonic stem cells (undifferentiated cells)
Crispr cas 9 - MORE SUCCESFUL AND FASTER
Explain how Embryo stem cells are used to create knockouts
When the mutation is induced eg by insertion of another gene this stem cell is injected into the BLASTOCYST EMBRYO (multicellular)
Transferred to a female mouse
Only some have mutations in their testes/ovaries (gametes)
Eventually pass on the mutation (takes long)
Explain how crispr cas 9 is used for gene editing / mutation induction
Cas 9 protein binds to a target DNA sequence called PAM
This is then unwound by guide rna
Cas9 protein double cuts the dna
When dna is repaired it can be faulty and therefore cause mutations eg insertion = gene knockout / not functioning
Explain how crispr cas can produce knockout mice faster
Mutation is induced in an embryo instead of blastocyst
(By crispr cas)
This embryo is injected into mother directly
Offspring develop with the mutation / NOT CHIMERAS
Why would using amino acid substitution instead of full gene knockout be better to study human malformations
Because it’s rare that genes are fully knocked out
What kind of mice can have conditional gene knockouts induced into them (specific cell type or duration)
Flox mice
What is gastrulation
Where 3 germ layers form in the early embryo
Name the 3 germ layers of embryo
Ectoderm (outer)
Endoderm (inner)
Mesoderm (middle)
What do germ layers have different about each other
Different cell types due to different morphogens
Eg skin cell is on endoderm
When do neural tube defects occur
Abnormalities in neurulation
What did gross morphology and histology (anatomical approach) find about neural tube malformations
Gross morphology found neural tube isn’t closed and embryos were short
Histology found that the floor plate of the neural tube was widened
Did tying the floor plate of neural tube together close it?
No - must be genetic
What gene was identified by genetic approach to cause neural tube defects and what signalling pathway was it part of
Vangl2 gene part of wnt signalling pathway
What does the wnt path regulate
Position of cells in the eyes
What movement does the wnt signalling pathway regulate
Convergence extension in gastrulation
What does disruption to convergence extension cause
Shortening and widening of embryo and opening of neural tube (prevents closure)
Why is detecting eg genes such as vangl1 for neural tube malformations important
Can do genetic counselling and predict likelihood of it in next kid
Which therapy was designed to prevent neural tube opening due to vangI 1 disruption to wnt signalling
Folic acid B vitamin
