Birth defects Flashcards
Major causes of birth defects (top 4)
- Unknown (40%)
- Multifactorial (25%)
(polygenic) - Chromosomal (15%)
- Monogenic (10%)
Mesonephric duct forms what?
- ductus deferens,
- seminal vesicle,
- Epididymis
VACTERL mneumonic for anatomic abnormalities that are more frequently associated with eachother
Vertebral anomalies Anal atresia Cardiac anomalies Tracheo- Esophageal fistula Renal Limb
Birth defects are found in what % of the total population (children –> adults?)
5-7%
*about 2% of infants are born with life threatening birth defects
Birth defects are the leading cause of _______
death outside of prematurity in the 1st year of life
Teratology
- what is it?
- What does it focus on?
the study of birth defects and the mechanisms responsible for them
- focus on “critical periods” of developmental susceptibility
- great picture in handout
Most common trisomy
trisomy 16, but they dont survive
Phocomelia is caused by what?
Specific limb defects
- Thalidomide before 5 weeks
Teratogens
- Thalidomide
- Vit A analogs
- Cholesterol synth inhibitors
- Anticonvulsants
- ACE inhibitors
- Ethylalcohol
*exogenous agents that disrupt developmental pathways causing birth defects
Give examples of:
- Tissues sharing gene expression
- Tissues related to each other thru location
- Tissues sharing developmental timing
- TIssues affected by interacting processes
- Tissues sharing gene expression
- Hedgehog signaling pathway - Tissues related to each other thru location
- branchial arches - Tissues sharing developmental timing
- embryonic inner cell mass - TIssues affected by interacting processes
- cell proliferation and apoptosis
Are phenotypes the result of intxns btwn environment or genetic factors?
both - duh
phenocopies
similar birth defects resulting from predominantly genetic or predominantly evironmental factors
*anything produced by genetic mutations can also be produced by environmental manipulations
Xenobiotics
compounds foreign to nature
- kill cells by directly causing toxicity by apoptotic pathways or disrupt surface intxn with other cells
- Depending on number of certain cells affected –> recognizable syndromes
Tetrology of fallot
- Supravalvular pulmonic stenosis
- Overridig aorta
- VSD
- RV hypertrophy
Most common genetic (chromosomal) mutation associated with TOF
- what other genetic syndromes are associated with ch 22?
- What environmental factor increases the risk of TOF?
deletion on ch 22q11
- associated with Shprintzen and diGeorge
- if these phenocopies are exposed to isotretinoin (Accutain), and Vit A analogue, then TOF is more likely
- itll stimulate the migration of neural crest cells in the region of the developing branchial crest and arches
