Birth Defects

Question 1

What are the 2 classes of transcription factors?

Answer 1

unspecific, general: CREB:

specific: HOX

Question 2

What would happen to if HOXA13 and HOXD13 were mutated?

Answer 2

disturb the development of the fingers and toes; as late hox genes are important for the development of the distal pole

Question 3

What is Shh secreted from?

Answer 3

notochord

Question 4

What is the role of Shh (2 things)

Answer 4

1. brain/spinal cord

2. posterior limb development

Question 5

If there is a mutation in Shh, what does this lead to in general?

Answer 5

Midline defects (failure to develop the midface and the forebrain)

Question 6

What is holoprosencephaly?

Answer 6

Caused by a mutation in Shh; midline defect

Question 7

What is important for Shh protein synthesis? If this isnt around, what disease can result?

Answer 7

cholesterol

Smith Lemli Opitz Syndrome: cause multiple severe congenital malformations

Question 8

During development, cells must respond to environmental clues by changing shape and polarity. Explain this process in the kidney.

Answer 8

1. kidney cells need to develop an apical and basal side

2. they do this by detecting a stream, which will cause cells to stop proliferating, causing correct polarization.

Question 9

What happens if polycystin 1 or 2 are mutated? what disease does this cause?

Answer 9

renders a cell incapable of sensing flow; no polarity developed

leads to polycystic kidney disease

Question 10

Explain the process of cell migration in the developing CNS.

Answer 10

1. neuronal stem cells of neural tube –> neuronal precursor cells
2. migrate outward from the ventricle along a scaffold of glial cells (occurs in waves)

Question 11

What occurs in a mutation of the LIS1 gene?

Answer 11

lissencephalpy; smooth brain; cells cant migrate

Question 12

Apoptosis is especially important for what 5 things?

Answer 12

1. heart
2. digits
3. anal
4. uterus and vagina connection
5. immune system

Question 13

True hermaphroditism? vs pseudohermaphroditism?

Answer 13

true: have both testes and ovaries
psuedo: patients pheno does not equal geno

Question 14

What are 2 reasons for chromosomal aberrations involving SRY leading to sex reversal disorders?

Answer 14

1. if sry is deleted on the Y chorm, the embryo develops into a female of XY
2. if sry is translocated to the X-chrom, the embryo develops into a male with an XX

Question 15

Adrenal hyperplasia is the most common cause for what?

Answer 15

female pseudohermaphroditism: caused by a defect in cortisol biosynthesis, so everythign shunted to androgen pathway

Question 16

What are 3 reasons for male pseudohermaphroditism?

Answer 16

1. defect in tests during embryogenesis
2. problem in androgen biosynthesis by the testes (5a-reductase)
3. deficiency in androgen receptor production or signaling by the target cells (androgen insensitivity syndrome)