Developmental Genetics

Question 1

Why is a Caenorhabditis elgans used?

Answer 1

• There exists a complete cell fate map

Question 2

Why is Drosophila melangaster used?

Answer 2

• easy to breed and lots of mutants.

Question 3

Why is Danio rerio used?

Answer 3

• Transparent embryos

Question 4

Why is Xenopus laevis used?

Answer 4

• Tetraploid

Question 5

Why is Gallus gallus used?

Answer 5

• Easy to observe and manipulate embryo.

Question 6

Why is Mus musculus used?

Answer 6

• Embryo manipulation challenging.

Question 7

Where are FGFR3 mutations found?

Answer 7

• One of the family of FGF receptors, expressed in growing bones.

Question 8

What are some symptoms of Achondroplasia?

Answer 8

Most common due to autosomal dominant FGFR3 mutations. Most common name is achondroplasia (disproportionately short stature (short limbs), Macrocephaly, moderate increase in FGFR3 activity that inhibits chondrocyte growth.

Question 9

What is a milder form and what is a more severe form of achondroplasia called?

Answer 9

Milder: hypochondroplasia -
Severe: Thanatophoric dysplasia - less lethal, very short limbs, highly activated receptor.

Question 10

What types of effects can transcription factors cause?

Answer 10

• Pleiotropic effects ( 1 gene multiple effects)

Question 11

What type of gene is the Sry gene?
What does it regulate?
What does it do in men and woman?

Answer 11

• Sex-determining region of Y
• Regulate Sox9 expression in the genital ridges.
• Increases in male, decreases in female

Question 12

What is camptomelic dysplasia?

Answer 12

• Mutation at Sox9 (regulates chondrogenesis and Col2A1). Short limbs, sex-reversal of XY fetuses.

Question 13

What occurs in Hirschsprungs and what is the significance of Sox10

Answer 13

Hirschsprung is a neural crest defect. Enteric neurons not developed properly (colon hypomotility and severe constipation). Sox10 one of several genes that cause similar phenotypes.

Question 14

What do integrins and Glycosyltransferases bind in the ECM?

Answer 14

• Integrins- link between ECM and cytoskeleton

- Glycosyltransferases: bind glycosyl residues on ECM

Question 15

What is the ECM mutation in osteogenesis imperfecta?

Answer 15

It is a type 1 collagen disorder that has mutations in the glycines disrupting fibril formation.

Question 16

Marfans Syndrome

Answer 16

Mutations on fibrillin-1 gene and elastin coordinate microfibril.
-Symp: Tall and lanky, hypermobile joints and arachnodactyly, and lens displacement

Question 17

Supravalvular aortic stenosis

Answer 17

Elastin mutations

Question 18

What occurs in junctional Epidermolysis bullosa?

Answer 18

• mutation in laminin which is important in anchoring cells to ECM. LAMC2 mutations.
  Symptoms epithelia not attach large blister form on skin

Question 19

What is sonic hedgehog involved in?

Answer 19

• Neural tube, somites, limbs

- Left-right axis

Question 20

What is Holoprosencephaly?

Answer 20

• is severe form
• SHH attaches to cholesterol in membrane - necessary for proper cell patterning, and midline brain defect caused by cholesterol biosynthesis inhibitors.

Question 21

What is Smith-Lemli-Opitz syndrome?

Answer 21

-

Question 22

What are the signals for Dorsal/Ventral Axis

Answer 22

• Noggin and chordin are dorsalizing signals
• Bmp4 is ventralizing signal
• Noggin and chordin bind Bmp4, prevent binding to receptors
• Anatagonistic pattern common in development

Question 23

What are the signals for Left/Right Axis?

Answer 23

When

Question 24

Fgf8 is a candidate for inductive signal

Answer 24

Wnt2b and Wnt8c maintain Fgf10

Question 25

Holt-Oram syndrome

Answer 25

Thumb, radius defects most common, T-box gene TBX mutated

Question 26

Ulnar-mammary syndrome

Answer 26

• TBX3 mutated closely linked.