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Fall-Foundational Sciences Year 1 > Development-Genetics > Flashcards

Development-Genetics Flashcards

1
Q

Pierre Robin sequence

presentation

A

history of oligohydramnios
airway obstructions
cleft lip
small lower jaw

cleft lip a result of an original kidney dysfunction

extensive surgery

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2
Q

Treacher Collins Syndrome

A

mutation in treacle protein, auto dominant so high recurrence risk

present: small jaw, slanting palpebral fissures, malar hypoplasia, craniofacial abnormalities, airway obstruction

family hx of similar minor anomilies

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3
Q

regulative phase

early development

A

> end of week 2

can lose cells but compensated or embryo is aborted “all or nothing”

genome is maximally unmethylated aka open for epigenetic programming

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4
Q

primitve streak

A

emergence of primitive streak ends regulative phase aka no compensation after develops

becomes notochord

node @anterior end of streak

anterior/posterior axis

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5
Q

nodal gene

A

required for formation of primitive streak

nodal protein = morphogen (control over morphogenesis by concentration gradient)
-from TGF-beta family

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6
Q

dorsal/ventral development

A

induced by noggin and chordin morphogens from node

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7
Q

left/right formation

A

sonic hedgehog - morphogen, asymmetry of expression

cilia generate unidirectional current

defects occur rarely aka situs inversus

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8
Q

pattern formation

A

Hox genes- transcription factors,

tissue development depend on which set of hox genes is expressed aka hox code (bc each tissue express diff combos)

provide positional info

humans have 4 clusters arranged head to toe

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9
Q

epigenetic regulation

during development/differentiation

A
  1. developmental methylation: as cell lineages differentiate
  2. environment induced methylation: starvation or stress in 1st trimester
  3. parent of origin imprinting: only one active copy of a gene either from mom or dad (monoallelic expression)
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10
Q

Imprinting cycle

A

in gametogenesis: mark parent of origin chromo/imprint by de novo methylation

early gametogenesis: erase old poo imprint by erase methylation pattern

before implantation: erase old developmental pattern by erase methylation

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11
Q

x chromasome inactivation

A

all but one x chromos are inactivated but some can escape

mediated by transcription of XIST gene

DNA methylated + histones deacteylated

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12
Q

dysmorphology

A

aka developmental anomalies

describe birth defects by cause and mechanism

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13
Q

malformations

A

intrinsic abnormality in dev process

i.e polydactyly from error in HOX signalling

cause of defect

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14
Q

deformations

A

from extrinsic influence on dev

i.e. lack of amniotic fluid prevent extension of limbs/impairs dev

cause of defects

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15
Q

dysplasia

A

abnormal organization of cells w/i tissue

i.e hypochondroplasia from premature ossification of cartilage

cause of defect

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16
Q

disruption

A

extrinsic destroys developing tissue, started normally then killed off

i.e. amniotic bands wrap around limbs and cut off blood supply = amputate

cause of defect

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17
Q

syndromes

A

single defect simultaneously affects dev of diff systems

i.e down syndrome

mechanism

18
Q

sequences

A

single defect that starts cascade of events

i.e Pierre Robin Sequence

mechanism

19
Q

extent of damage

A

week 1-4 (blastogenesis): multiple major abnormalities in major organs/entire embryonic regions
week 5-8 (organogenesis): abnorms in specific organs, single major anomalies
week 9+ (post organ formation): mild effects

20
Q

VACTERL association

A

group of birth defects for unknown reasons occur together, need 3+ for dx

V = vertebral
A= anal atresia
C= cardiac abnormalities
T= tracheo
E=esophagal fistual
R= renal
L=limb abnormalities

-assume blastogenesis phase
-maternal diabetes known risk factor

21
Q

regulation of dev

A

36 cell divisions

one extra round likely fatal if early
segmental overgrowth if late

22
Q

cellular processes driving development

A
  1. gene regulation (transcription factors and epigenetics)
  2. cell to cell signalling (morphogens)
  3. dev of cell shape/polarity (cytoskeletal changes)
  4. movement and migration of cells
  5. programmed cell death (apoptosis)
23
Q

gene regulation in dev

A

transcription factors are transient
-general (CREBBP) or specific (HOX)

TF binding needs to be re-est after cell division bc no memory

24
Q

CREBBP

A

general TF, also called CBP

defect causees Rubinstein-Taybi Syndrome

affects CNS, eyes, heart, kidney

25
Q

cell to cell signalling

direct

A

direct contact: juxtacrine
-cell to cell = notch, cadherin
-cell to matrix = integrin

26
Q

cell to cell signalling

indirect

A

or paracrine/autocine diffusible morphogens:
-bind to receptors in plasma mem
-cells obtain position info from morpho concentration
-morpho binding triggers signalling cascades and activates TFs

27
Q

sonic hedgehog morphogen

A

binds Patched receptor > activates Smoothened protein = activiates large # TFs
-stops cleavage of GLI protein (glioma assoc oncogene)

requires cholesterol for signalling

patch binding activates large # TFs

28
Q

Shh secretion and effect

A

1.organizes brain and spinal chord cells
-secreted from notochord and floorplate of neural tube = midline defects if Shh defect

  1. limb development
    -secreted from cells in polarizing region of limb bud so transplantation to anterior region = duplication of posterior limb elements
29
Q

Shh defects

A

midline and holoprosencephaly (forebrain not split into two halves)

mutations are autosomal dominant w/ variable expressivity

Smith Lemli Opitz syndrome= autosomal recessive from cholesterol syn defects impacts Shh signalling

30
Q

Retinoic acid

A

binds retinoic acid receptors RAR/RAX

-modulates HOX expression
-retinol acne cream is a teratogen aka if during pregnancy then complications/defects

31
Q

Wnt

A

binds Frizzled receptors
-inc cellular catenin levels (cancer)

32
Q

polycystic kidney disease

A

normally: cells sense flow thru tubule and polarize by relocating erb-b2/ECFR from luminal to basal side

cells still have erb-b2/EGFR exposed to lumen (not relocated) so epithelial cells still respond to growth factors = cysts

33
Q

LIS1 Mutations

A

interferes with migration of neuronal precursor cells outward = lissencephaly (smooth brain)

normally migrate from ventricle along scaffold of glial cells

34
Q

apoptosis

A

necessary for
1. dev of heart
2. separation of digits
3. perforation of anal and choanal membranes
4. est of connnection b/t uterus and vagina
5. dev of immune system (eliminate cells that react to self)

35
Q

disorders sexual development

DSD

A

ovotesticular DSD: indivs with both testes and ovaries, very rare

more freq: presence of both but external genitalia not match gonasds/present ambiguously

normal: SRY (sex determining region) initiates male dev, androgrens from testes drive dev of male genitalia

36
Q

DSD molecular causes

SRY

A

Y chromo w/o functional SRY = XY female

X chromo with translocated SRY = XX males

37
Q

DSD molecular causes

enzymes/receptors

A

androgen insufficiency w/testes = XY

androgen syn w/o testes = XX

38
Q

congenital adrenal hyperplasia

A

defect in cortisol and aldosterone production from deficiency in sterioid 21-hydroxylase
-life threatening bc low BP and addisonian shock (stress response shock)

intermeds shunted into androgen production

46, XX DSD
masculinization of female babies (androgen syn w/o testes)

39
Q

androgen insensitivity

A

46, XY, deficient androgen production or poor response but have testes
-incomplete dev of testes during embryogenesis
-deficient steroid 5alpha-reductase

androgen insensitivity syndrome

40
Q

cancer

A

incompletely differntiated cells might proliferate and become progenitor cells for tumors

41
Q

synpolydactyly

A

extra digits + fused
distal HOX genes so specific transcription factor defect

autosomal dominant so if parents then also child

Fall-Foundational Sciences Year 1 (33 decks)

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