Lecture 8: Birth Defects Flashcards
What is the most common birth defect?
Congenital heart defects
What are the known causes of birth defects?
twinning
genetics (xs abnormalities, gene mutations)
environmental factors
gene + environment (multifactorial inheritance)
What kind of birth defect is Turner syndrome an example of?
Monosomy (X)
What is the inheritance pattern of Axenfeld-Rieger syndrome?
autosomal dominant
As seen in Axenfeld-Rieger syndrome, mutations in ______ can alter the development of multiple systems.
single genes
What are symptoms of Axenfeld-Rieger syndrome?
ocular defects dental abnormalities widely spaced eyes prominent forehead extra folds around belly button
What genes are known to be mutated in Axenfeld-Rieger syndrome? what role do they have?
PITX2
FOXC1
embryonic development
What is the difference between monogenic traits and complex traits?
complex traits have many contributing genes and non-genetic influences
What do genetic factors called modifier genes contribute to?
complex traits
What are three genetic causes of holoprosencephaly?
xs abnormality (#, structure) env condition (maternal diabetes) single gene mutations
In what diease are SHH, PTCH1, GLI2, and DISP1 involved?
holoprosencephaly
What is an example of an infectious agent which causes birth defects?
Rubella –> Congenital Rubella Syndrome
What structure can have a birth defect due to hyperthermia (fever)?
neural tube defects
Coxackie virus, Cytomegalovirus, herpes simplex, parvovirus, rubella (German measles), Toxoplasma gondii (toxoplasmosis), Treponema pallidum (syphilis) are all _______ which can cause _______
infectious agents
birth defects
What birth defect did thalidomide cause?
phocomelia (limb defects)
What are two prevalent hypotheses for how thalidomide caused birth defects?
- inducing oxidative stress
2. disrupting angiogenesis
What are the names for the study of birth defects, and for agents which cause birth defects?
teratology
teratrogens
On what factors does susceptibility of teratogens depend?
development stage at time of exposure
dosage and duration of exposure
genotype (embryo or mom) - gene-env interations
What is the most sensitive period for inducing birth defects?
weeks 3-8 during embryogenesis
People with _____ can have trouble learning and remembering, understanding and following directions, controlling emotions, communicating and socializing, and with daily skills
Fetal Alcohol Syndrome (FAS)
Fetal Alcohol Spectrum Disorders (FASD)
Microcephaly, indistinct philtrum, narrow upper lip, low nose bridge, and flat midface all characterize what?
Fetal Alcohol Syndrome
With what cell processes is alcohol thought to interfere?
migration adhesion proliferation survival signaling gene expression
What type of antidepressants have been associated with a low risk of birth defects?
SSRIs (selective seratonin reuptake inhibitors)
What are the majority of congenital heart defects due to?
Multifactorial - genes + env
What do congenital heart defects change?
route of blood flow
What results from a septal defect?
A hole in the heart
What are the two causes of septal defects?
Excessive cell death
Inadequate septum development
What is it called when the heart is positioned on the right side of the thorax instead of the left?
Dextrocardia
What is double outlet right ventricle?
Aorta comes from right ventricle (instead of left)
