Malformations And Teratology Flashcards
Describe a syndrome anomaly.
Single etiology leads to multiple anomalies commonly found together.
Describe an association anomaly.
Multiple anomalies appear together more often than expected due to individual frequencies as well, but they are not related to a single known etiology.
Describe a sequence anomaly.
One of multiple issues can give rise to a single known condition, which then results in multiple related anomalies.
Ex. One of several factors (PKC, urethral obstruction, etc) can give rise to oligohydramnios, which then has multiple resulting anomalies in its phenotype).
Describe a developmental field anomaly.
Multiple anomalies, possible of different tissue types, within a single area exist due to dysfunction with neighborhood developmental signals.
Describe a malformation.
An error in morphogenesis leads to the anomaly. The process did not start right and it can affect multiple tissue types.
Define a disruption anomaly.
Tissue formation began correctly, but in utero destruction of its formation before development was finished causes the anomaly (ex. Teratogen effects).
Describe a deformation.
Mechanical forces lead to a size or shape change anomaly in the developing structure (ex. Insufficient uterine space for development).
Describe a dysplasia anomaly.
Caused by abnormal organization or function of a specific tissue type throughout the body, for example skeletal anomalies like achondroplasia.
What is necessary for teratogen exposure to be diagnosis?
- Maternal exposure, not a phenocopy.
- Exposure during a critical period for a significant amount of time.
- Exposure included a dose over a necessary threshold.
- Nature of the teratogen, for instance if it can adequately cross into fetal circulation.
- Observance of a set deviation from mean standards, as teratogens cause with without deviation.
- Genetics of the mother and fetus (thus indirectly father as well), which can affect dose, timing, or nature necessary to have an effect.
What are the stages during which teratogen exposure has known effects?
Preimplantation- All or nothing effect, either pregnancy is lost or no damage occurs.
Organogenesis- Most sensitive, leads to anomalies in organs.
Functional maturation- Behavioral teratogens as they often affect the CNS at this point, or metabolic teratogens.
Define thalidimide’s function as a teratogen.
Must be taken during a critical period or organogenesis.
Dose dependent response causing limb reduction, heart defects, cleft lip, and ear malformations.
Describe ionizing radiation as a teratogen.
0-14 days: All or none
2-15 weeks: Dose based response causing microcephaly, induction or cancer, intellectual disability.
Later: Increased risk for leukemia, intellectual disability.
Describe rubella as a teratogen.
1st trimester- Microcephaly, intellectual disability, cataracts, congenital heart defects.
Later- Intrauterine growth retardation.
Describe alcohol as a teratogen.
Over two ounces per day causes FAS, resulting in decreased brain development, distinctive facial features, and behavioral issues.
Later can cause FAE with similar but less dramatic effects.
Describe smoking as a teratogen.
Increases likelihood of preterm delivery, low birth rate, cleft palate, and SIDS.
