Congenital Malformations

Question 1

What 2 factors cause congenital malformations

Answer 1

Genetics and environment

Question 2

Give 2 examples of how environment can cause malformation

Answer 2

Drugs - acne treatments have RA which affects the midbrain development

Diabetes

Question 3

What 3 reasons do we study malformation

Answer 3

1- identify cause and understand

2- predict future occurrences (genetic counselling)

3- prevention of them developing treatment

Question 4

What 2 histological techniques are used in the anatomical approach to what the malformations are

Answer 4

1- gross morphology : dissection to see the organs in detail

2- histology : cut slices into dehydrated cell tissues of embryo and see tissues closely

Question 5

What is used in histology

Answer 5

Paraffin wax

Question 6

What are 3 ways we can manipulate the embryo to see what causes malformations

Answer 6

Removal of a specific part eg the node

Replacing a part with another

Drug interference

Question 7

What is the genetic approach to studying malformations and how is it useful

Answer 7

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)

Question 8

What 4 techniques does genetic approach use to study malformations / map gene expression

Answer 8

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)

Question 9

What 3 ways can you detect gene expression and analyse it

Answer 9

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

Question 10

Why is single cell (isolation from embryo) rna sequencing important

Answer 10

It is used to map all the genes and when in development it’s expressed

Question 11

What 2 ways can knockout mice be produced and show which one is faster and successful

Answer 11

Using embryonic stem cells (undifferentiated cells)

Crispr cas 9 - MORE SUCCESFUL AND FASTER

Question 12

Explain how Embryo stem cells are used to create knockouts

Answer 12

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)

Question 13

Explain how crispr cas 9 is used for gene editing / mutation induction

Answer 13

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

Question 14

Explain how crispr cas can produce knockout mice faster

Answer 14

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

Question 15

Why would using amino acid substitution instead of full gene knockout be better to study human malformations

Answer 15

Because it’s rare that genes are fully knocked out

Question 16

What kind of mice can have conditional gene knockouts induced into them (specific cell type or duration)

Answer 16

Flox mice

Question 17

What is gastrulation

Answer 17

Where 3 germ layers form in the early embryo

Question 18

Name the 3 germ layers of embryo

Answer 18

Ectoderm (outer)

Endoderm (inner)

Mesoderm (middle)

Question 19

What do germ layers have different about each other

Answer 19

Different cell types due to different morphogens

Eg skin cell is on endoderm

Question 20

When do neural tube defects occur

Answer 20

Abnormalities in neurulation

Question 21

What did gross morphology and histology (anatomical approach) find about neural tube malformations

Answer 21

Gross morphology found neural tube isn’t closed and embryos were short

Histology found that the floor plate of the neural tube was widened

Question 22

Did tying the floor plate of neural tube together close it?

Answer 22

No - must be genetic

Question 23

What gene was identified by genetic approach to cause neural tube defects and what signalling pathway was it part of

Answer 23

Vangl2 gene part of wnt signalling pathway

Question 24

What does the wnt path regulate

Answer 24

Position of cells in the eyes

Question 25

What movement does the wnt signalling pathway regulate

Answer 25

Convergence extension in gastrulation

Question 26

What does disruption to convergence extension cause

Answer 26

Shortening and widening of embryo and opening of neural tube (prevents closure)

Question 27

Why is detecting eg genes such as vangl1 for neural tube malformations important

Answer 27

Can do genetic counselling and predict likelihood of it in next kid

Question 28

Which therapy was designed to prevent neural tube opening due to vangI 1 disruption to wnt signalling

Answer 28

Folic acid B vitamin