19. Developmental Genetics

Question 1

What are 3 genetic mediators?

Answer 1

1. Paracrine Signaling
2. DNA transcription factors
3. ECM proteins

Question 2

Receptor that receives ligands by paracrine signaling that can be mutated leading to skeletal dysplasias. (Achondroplasia, hypochondroplasia, thanatophoric dysplasia)

Answer 2

Fibroblast Growth Factor Receptor 3

FGFR3

Question 3

Gene that regulates transcription factor SOX-9 expression in the genital ridges.

Answer 3

Sry gene

Question 4

Transcription factor that regulates the gene Col2A1 which deals with chondrogenesis. Mutations can lead to short limbs or even sex reversal so that an XY genotype develops as a female.

Answer 4

SOX-9

Question 5

Transcription factor that moderates proliferation and migration of neural crest cells. Mutation can lead to Hirschsprung’s Disease.

Answer 5

SOX-10

Question 6

Mutation in collagen type 1 can prevent proline from being incorporated into the tight fibrillar collagen triple helix leading to this disorder…

Answer 6

Osteogenesis Imperfecta

Question 7

Disorder that results from a mutation in the Fibrillin-1 gene.

Answer 7

Marfan Syndrome

Question 8

Mutations in the gene LAMC2 prevent laminin formation leading to this disorder…

Answer 8

Epidermolysis Bullosa

Question 9

Protein that decides the fate of cells in a developing embryo. Decides left/right axis and which cells form neural tube, somites, and limbs.

Answer 9

Sonic Hedgehog (SHH) protein

Question 10

Mutation in either the SHH protein or cholesterol biosynthesis that leads to midline defects and brain malformation.

Answer 10

Holoprosencephaly

Question 11

Component of the cell membrane that SHH protein must bind in order to signal the cell to differentiate into certain tissues.

Answer 11

Cholesterol

Question 12

Inability to synthesize cholesterol leading to defects similar to SHH protein mutations.

Answer 12

Smith-Lemli-Opitz syndrome

Question 13

Patterns of cell differentiation along the primitive streak in embryo development are due to these genes.

Answer 13

HOX-genes

Question 14

2 HOX-genes that send dorsalizing signal to cells so that they form on the dorsal aspect of the organism.

Answer 14

1. Noggin
2. Chordin
   (actually they just bind Bmp4 which prevents ventral signals from being sent to cells that should be dorsal)

Question 15

HOX-gene that signals cells to form on the ventral aspect of an organism.

Answer 15

Bmp4

Question 16

Protein that sends a signal to induce the entire process of limb formation.

Answer 16

Fibroblast Growth Factor 8 (FGF-8)

Question 17

3 proteins that moderate proximal vs. distal growth of limbs.

Answer 17

1. FGF-2
2. FGF-4
3. FGF-8

Question 18

Mutation in the Tbox gene TBX5 leads to thumb and radial defects in this condition.

Answer 18

Holt-Ogram Syndrome

Question 19

Mutation in the Tbox gene TBX3 leads to posterior digit defects in this condition

Answer 19

Ulnar-mammary syndrome

Question 20

Gene that promotes insulin production in the adult but serves to allow pancreatic formation in the fetus.

Answer 20

Insulin Producing Factor 1 (IPF1)