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Biochem V > Birth Defects > Flashcards

Flashcards in Birth Defects Deck (63):
1

What is synpolydactyly?

extra digits that are fused with other digits

2

What are two types of txn factors?

specific and unspecific

3

The HOX family of genes is important for what?

patterning along the anterior-posterior border

4

What are the late HOX genes, 11 to 13, involved in?

development of the distal pole of the limbs

5

What is a morphogen?

substance secreted by cells in one part of the embryo

6

Where is Shh secreted from?

notochord and floor plate of neural tube

7

A defect in Shh secretion leads to what?

midline defects

8

What developmental protein must interact with cholesterol to function?

Shh

9

What disease features an impairment of Shh function due to a defect in cholesterol biosynthesis?

Smith-Lemli-Opitz Syndrome

10

What two genes are involved in detecting fluid flow in the developing kidney?

polycystin 1 and polycystin2

11

What do defects in polycystin 1 and 2 cause? What disease develops?

patient to not polarize cells and cysts to develop

polycystic kidney disease types 1 and 2

12

Where does development of the CNS begin from?

neural tube

13

What gene interferes with migration of neural cells?

LIS1

14

What condition results from defects in the LIS1 gene?

lissencephaly

15

What is true hermaphroditism?

patient has both testes and ovarian tissue

16

What is pseudohermaphroditism?

pts have either testes or ovarian tissue but the phenotype does not represent the sex

17

Where is the testes determining factor located?

SDR of the Y chromosome (SRY)

18

What happes if SRY is deleted on the Y chromosome?

female with XY karyotype

19

What happes if SRY is translocated to the X-chromosome?

the embryo develops into a male with an XX karyotype

20

What are female pseudohermaphrodites?

normal ovaries but ambiguous or male genitalia

21

What is the most common cause for female pseudohermaphroditism?

congenital adrenal hyperplasia

22

CAH often involves a defect in what enzyme?

21-hydroxylase

23

What does a defect in 21-hydroxylase result in?

block in cortisol synthesis with intermediates being shunted into androgen synthesis pathways

24

Where/when do specific txn factors function?

specific cells at specific times

25

HOX 11-13 are involved in what?

development of the distal pole of the limbs

26

Where is Shh secreted from?

notochord and floor plate (of developing neural tube)

27

Where does Shh diffuse to?

ventral side of body

28

Where does Shh influence cell development?

brain and spinal cord

29

A defective Shh leads to inability to develop what two structures?

midface and forebrain

30

Other than the notochord and floor plate, where else is Shh secreted from?

developing limb

31

At the developing limb, what does Shh secretion induce?

posterior limb elements

32

What compound must Shh interact with to function properly?

cholesterol

33

How does Smith-Lemli-Opitz affect Shh signaling?

it is a cholesterol biosynthesis condition

34

Defects in polycystin 1 or 2 impede a cells ability to sense what?

fluid flow

35

How do epithelial kidney tubules become polarized?

sensing fluid flow

36

A genetic defect in polycystin 1 or polycystin 2 results in what disease?

polycystic kidney disease

37

Where does development of the CNS occur?

neural tube

38

What gene is involved in the orderly migration of cerebral cortex cells?

LIS1

39

What five tissues require apoptosis for their development?

heart, digits, anus, uterus/vagina, immune system

40

What is true hermaphroditism?

patient has both testes and ovarian tissue

41

What is pseudohermaphroditism?

patient has testes or ovaries but their phenotype does not match their genetic makeup

42

What part of the Y chromosome drives male development?

Sex-determining region of Y (SRY)

43

Within the SRY, what gene determines male development?

Testes Determining Factor (TDF)

44

What happens if the SRY is deleted?

embryo develops in an XY female

45

What happens if SRY is translocated onto the X chromosome?

XX, male

46

Female pseudohermaphrodites possess what?

normal ovaries but ambiguous or male genitalia

47

What is the most common cause for female pseudohermaphroditism?

congenital adrenal hyperplasia

48

Congenital adrenal hyperplasia is caused by what defective enzyme?

21-beta-hydroxylase

49

The production of what product involves 21-hydroxylase?

cortisol

50

With a block in synthesis, where do cortisol substituents get shunted to?

production of androgens

51

The development of male sex characteristics are driven by what?

androgens

52

What enzyme can be implicated in the lack of development of male sex characteristics?

5-alpha-reductase

53

What is androgen insensitivity syndrome?

deficiency in androgen receptor production

54

What does the tumor progenitor model predict?

epigenetic programming errors lay the seed for cancer later in life

55

What do high concentrations of Shh induce? Low concentration?

high = floor plate

low = motor neurons

56

A defect in CREB results in what disease?

Rubinstein Taybi

57

Renal tubules polarize by moving what receptor?

EGFR

58

Where does development of the CNS begin from?

neural tube

59

Neuronal precursor cells begin their migration from where? What do they use as a scaffold for migration?

ventricles

glial cells

60

Where is the testis determining factor located?

SRY

61

What is the most common cause for female pseudohermaphroditism?

congenital adrenal hyperplasia

62

What enzyme is often absent in male pseudohermaphroditism?

5-alpha reductase

63

Why does a deficiency in 5-alpha reductase cause male pseudohermaphroditism?

lack of androgen production