AssessmentsFetal alcohol syndrome
Fetal alcohol syndrome
USMLE® Step 1 style questions USMLE
USMLE® Step 2 style questions USMLE
A newborn infant is reviewed on the maternity unit because he was born small for his gestational age. His mother says that her pregnancy was uneventful and that she was able to continue with her life with no real abnormalities. Examination shows a smooth philtrum of the lip, microcephaly, and midfacial hypoplasia. Which of the following teratogen was the infant most likely exposed to prenatally?
Fetal alcohol syndrome, or FAS, occurs because of maternal use of alcohol during pregnancy.
It’s currently the leading cause of intellectual disability in the US and can cause characteristic physical abnormalities.
Normally, the fetus is connected to the placenta by the umbilical cord, so the fetus gets oxygen and nutrients from the mother.
Unfortunately, ethanol and toxic alcohol metabolites like acetaldehyde also pass freely through the placenta, but the fetal liver doesn’t have the necessary enzymes to metabolize them, so they build up inside the fetus really fast.
In FAS, ethanol interferes with cell division and proliferation, cell growth and differentiation, and with the migration of mature cells to their final location in the developing embryo, which affects the development of various fetal tissues, including the brain.
Alcohol-induced brain damage includes partial or complete agenesis of the corpus callosum, which links the two hemispheres together, so it either forms incompletely, or not at all.
This causes intellectual disability and seizures.
When the frontal cortex and the hippocampus are affected, this causes poor memory and communication skills, as well as intellectual disability.
The most common symptom of FAS is growth retardation, resulting in low height and weight.