Day 13, Lecture 2: Human Development: Postnatal Development/Dysmorphology Flashcards Preview

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Flashcards in Day 13, Lecture 2: Human Development: Postnatal Development/Dysmorphology Deck (28):

in 2002, __% of infnt deaths were attributed to birth defects 



in 2002, ___% of infant deaths were the result of prematurity, a failure of maintenance of maternal-fetal developmental environment



Genetic counseling when birth defects are identified prenatally provide an an option for parents to decide to 

  • terminate or continue pregnancy
    • Public health goal is not, however, to prevent births of children with birth defects 


Prevention of birth defects is preferred, and can be accomplished through

  • Premarital couseling
    • esp. if birth defects run in family, or if there is consaguinity
  • Folate supplementation> 3 months prior to conception
  • Optimization of maternal health (e.g. diabetes, hypertension)
  • Careful selection of maternal medication (e.g. anti-convulsants, anti-depressants)


What is Dysmorphology

  • Branch of medical genetics that interprets patterns of human growth and structural defects
  • dys-
    • abnorma/disordered
  • morph-
    • Form/shape
  • Other terms:
    • (Major) congenital anomaly
    • (Major) birth defect


Does congential imply a genetic etiology

  • No
    • ex. 
      • exposure to alcohol, valproic acid (anti-convulsant), retinoic acid (acne medication), or methotrexate (an aborteficiens, chemotherapeutic) during pregnancy may cause severe congenital anomalies 


Major vs. Minor Anomalies


Major anomaly examples

  • Congenital heart defect
  • Anterior abdominal wall defect
  • meningomyelocele
  • Hydrocephalus
  • Ambiguous genitalia
  • Cleft lip and/or cleft palate


Examples of Minor Anomalies


Relevance of Minor anomalies

  • About 15% of all newborn babies will have at least one minor malformation, and these usually go unnoticed
  • However, their presence should prompt the clinician to look for a major malformation
  • Risk for major anomaly is increased markedly if >2 minor anomalies are present:
    • If there are no minor malformations, the risk of a major malformation is 1.4%
    • If ther is 1 minor malformation, the risk of a major malformation is 3%
    • If there are 2 minor malformations, the risk of a major malformation is 11%
    • If there are 3 or more malformations, the risk of a major malformation is 20%
  • both major and minor anomalis:
    • may be associated with particular syndromes
    • may be an isolated finding in an otherwise healthy individual
  • For example, a cleft lip or palate may be an isolated finding (non-syndromic) in an otherwise healthy individual, or may be part of a syndrome in an individual with multiple birth defects 




What is a syndrome

  • A syndrome is generally recognized and defined as a well-characterized constellation of major and minor anomalies that occur together in a predictable fashion presumably due to a single underlying etiology which may be monogenic, chromosomal, mitochondrial, or teratogenic in origin 


Williams syndrome 

  • due to a contiguous gene deletion on 7q11
  • Features:
    • Developmental delay
    • dysmorphic features
    • Supravalvular aortic stenosis 




what is an Association

  • An association is a group of anomalies that occur more frequently together than would be expected by chance alone but that do not have a predictable pattern of recognition and/or suspected unified underlying etiology
      • (anal atresia, cardiac anomalies, tracheoesophageal fistula or esophageal atresia, renal/urinary anomalies and limb defect) 


What is a sequence

  • is a group of related anomalies that generally stem from a single initial major anomaly that alters the development of other surrounding or related tissues or strucutures 
    • examples
      • Spina Bifida with changes to the lower extremities and disruption of bowel and bladder dysfunction would be another example of a sequence or field defect 
      • Potter syndrome
      • Pierre-Robin



What is a malformation

  • A malformation signifies that fetal growth and development did not proceed normally due to underlying genetic, epigenetic, or environmental factors that altered the development of a particular structure 


What is a deformation

  • A deformation is caused by an abnormal external force on the fetus during in utero development that resulted in abnormal growth or formation of the fetal structure 


What is a Disruption 

  • A disruption occurs when a fetal strucutre is growing normally and then growth is arrested due to something which disrupts the process. 
    • Ex. Amniotic banding



What is Dysplasia

  • Dysplasia occurs when the intrinsic cellular architecture of a tissue is not normally maintained throughout growth and development
    • Many of the skeletal syndromes of short stature are due to dysplasia in the developing bone and carilage 







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