Scientists from the University of North Carolina (UNC), Duke University, and University College of London, have been looking at how the timing of alcohol exposure during pregnancy can cause specific kinds of defects.
Fetal alcohol syndrome (FAS) affects 1-in-750 live births in the U.S. While clinicians typically look for classical FAS facial features in making a diagnosis, the effects of FAS can vary considerably and affected infants sometimes don't exhibit facial characteristics at all.
The new research, led by Kathleen K. Sulik, a professor in the Department of Cell and Developmental Biology at UNC, illustrates how the precise timing of alcohol exposure determines the specific kinds of defects.
In their animal-based studies, the researchers treated one group of mice with alcohol on their seventh day of pregnancy, a time corresponding to the third week of pregnancy in humans. A second group of mice was treated just 36 hours later, approximating the fourth week of human pregnancy. The amount of alcohol given was large, "high doses that most women wouldn't achieve unless they were alcoholic and had a tolerance for alcohol," Sulik said. Near the end of pregnancy, the fetuses were subjected to rigourous analyses.
The team found that the earlier alcohol exposure time elicited the classic FAS facial features, including characteristic abnormalities of the upper lip and eyes. What they observed in fetuses exposed just 36 hours later, however, was a surprise. These mice exhibited unique and in some cases opposing facial patterns, such as shortened upper lip, a present philtrum, and the brain, instead of appearing too narrow in the front, appeared wide.
"Overall, the results of our studies show that alcohol can cause more than one pattern of birth defects, and that the type and extent of brain abnormalities - which are the most devastating manifestation of prenatal alcohol exposure - in some cases may be predicted by specific facial features," Sulik said. "And, importantly, alcohol can cause tremendously devastating and permanent damage at a time in development when most women don't recognize that they're pregnant."
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Source: University of North Carolina Health Care