Asynchronous Dev. Genetics Flashcards Preview

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Flashcards in Asynchronous Dev. Genetics Deck (13):

describe malformations

  • abnormality that arises because of a primary error in morphogenesis due to an abnormal developmental process
    • due to errors occurring in the initial formation of strcuture; a primary structural defect of an organ or part of an organ 
  • ex: congenital heart abnormalities, cleft lip, 


describe sequence

  • sequence aka malformation sequence
    • cascade of effect resulting from a single primary malformation
      • multiple defects caused by primary problem
    • Pierre-Robin sequnce = head and facial abnormalities


describe syndrome (aka malformation syndrome)

  • pattern of features that known to have a unifying underlying cause
    • manifestations arise from several different points during morphogenesis
  • example = Down syndrome
    • not all features need to be present to make diagnosis


describe disruption

  • due to destructino of a tissue or organ after it is formed
  • results in an abnormal structure of a tissue or organ or as a result of external forces
  • usually not a genetically controlled event
    • ex: amniotic band disruption, can lead to amputation


describe deformations

  • deformations might be thought of as a mechanical distortions by a physical force upon an otherwise normal structure
  • occurs while tissue is forming
    • clubfoot is caused by lack of amniotic fluid
    • might be surgically corrected


describe dysplasia

  • an abnormality in a tissue structure caused by abnormal cellular organization
  • ex: FGFR3 mutation (achondroplasia) which affects many aspects of skeletal structure


describe association

  • traits coincide more often than expected by chance
    • traits are seemingly unconnected
    • a single genetic cause is not known
  • only a subset of conditions are needed to fit


describe SHH

  • involved in dorsal/ventral patterning
  • SHH is expressed at different temporal periods during development to control different areas
  • SHH also establishes the zone of polarizing activity
    • involved in limb patterning


describe the pathway of SHH

  • the normal function of PTCH is to inhibit SMO but when SHH is bound to PTCH, SMO is free to activate downstream signaling
  • GLI protein and CREBBP interact and activate gene expression by binding regulatory sequence on the DNA


describe function of HOX

  • HOX genes pattern the anterior/posterior axis of the embryo
  • In the limb bud, HOX gene expression is established as a result of the generation of a gradient of SHH protein that is produced by the Zone of Polarizing Activity (ZPA)


HOX genes encode ______

HOX genes encode transcription factors

  • Typically, these TFs must dimerize to bind to DNA
  • May be homodimers
  • May be heterodimers


describe HOX genes during development

  • HOX genes arranged in clusters (normal genes are not arranged in clusters)
  • As a body segment (or body part) needs instruction to develop, the next HOX gene is expressed
    • sequential expression during development controls body part formation during development 


describe the function of FGFR3

  • FGFR3 is a transmembrane receptor tyrosine kinase
  • G380R mutation of FGFR3 causes unregulated activity
  • Growth plate is prematurely converted to bone