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

Question 1

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

Answer 1

20%

Question 2

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

Answer 2

20%

Question 3

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

Answer 3

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

Question 4

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

Answer 4

• 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)

Question 5

What is Dysmorphology

Answer 5

• 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

Question 6

Does congential imply a genetic etiology

Answer 6

• 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

Question 7

Major vs. Minor Anomalies

Answer 7

Question 8

Major anomaly examples

Answer 8

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

Question 9

Examples of Minor Anomalies

Answer 9

Question 10

Relevance of Minor anomalies

Answer 10

• 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

Question 11

Question 12

What is a syndrome

Answer 12

• 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

Question 13

Williams syndrome

Answer 13

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

Question 14

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Question 16

what is an Association

Answer 16

• 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
  
  • VACTERL
    
    • (anal atresia, cardiac anomalies, tracheoesophageal fistula or esophageal atresia, renal/urinary anomalies and limb defect)

Question 17

What is a sequence

Answer 17

• 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

Question 18

Question 19

What is a malformation

Answer 19

• 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

Question 20

What is a deformation

Answer 20

• 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

Question 21

What is a Disruption

Answer 21

• 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

Question 22

What is Dysplasia

Answer 22

• 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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