Lecture 9: Birth Defects Flashcards
Environmental agents that cause birth defects are referred to as ? and the study of environmental causes of birth defects is known as ? ?
Teratogens, teratology.
Name some general representative agents that cause birth defects (teratogens).
Infectious agents, physical agents (hyperthermia or X-
rays for example), chemical agents and maternal conditions such as autoimmune disease or diabetes.
Thalidomide use my mother causes what defect in child? What 2 possible mech’s account for this affect?
Phocomelia. Oxidative stress or disruption of angiogenesis.
Hallmarks of congenital rubella syndrome
Microcephaly, PDA, cataracts.
Many genes have been implicated in HPE. Many of these operate in what ptwy?
Hedgehog signaling pathway.
There are multiple causes for some developmental
defects such as holoprosencephaly. What can these be?
Congenital anomalies such as this can be caused by chromosome abnormalities (struc & #), single gene mutations, environmental factors (maternal diabetes).
Define birth defect.
Congenital malformation. Structural, functional or behavioral disorder present at birth. Happens during embryogenesis and is present at birth.
Axenfeld-Rieger syndrome is an example of a multisystem
genetic birth defect caused by a [blank]. What interacts with the mutated gene that impacts how severe the mutation might be?
Single gene mutation (PITX2 and FOXC1). These genes appear to play important roles in embryonic development, particularly in the formation of structures in the anterior segment of the eye. Modifier genes, environment, diet, biochem interactions.
Hyperthermia secondary to infection can interfere with
? and cause ??
Neurulation, neural tube defects from lack of closure. Not a problem after closure.
Environmental factors that cause birth defects
Drugs, ionizing radiation, hyperthermia, infectious organisms, metabolic conditions in mother.
If embryo can’t get through gastrulation (1st 2 weeks of embryogenesis, malformation results in death. Thus, the embryo is most susceptible to birth defects during what time period of development?
Embryogenesis: weeks 3-8 of development.
Fetal alcohol syndrome (FAS) is the most serious type of FASD and includes what 3 general problems?
Structural defects, growth deficiency and intellectual disability.
What are the proposed mechanisms of alcohol teratologic effects?
Cell migration and adhesion, cell proliferation and survival,
and cell signaling and gene expression.
Heterotaxy can result in several congenital heart malformations including what?
Septal defects, double outlet right ventricle (DORV) and transposition of the great arteries.
What are some signs and symptoms used to identify a cong heart defect?
Rapid breathing, cyanosis, fatigue, poor blood circulation.
