Prenatal genetic test may cause birth defects
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A type of prenatal test that helps families learn of any serious genetic diseases in a fetus appears to increase the risk of certain birth defects, according to a study published today in the Journal of Craniofacial Surgery.
The test, called chorionic villus sampling, or CVS, is commonly performed in the first trimester of pregnancy. During CVS, a small sample of the placenta is removed to test for genetic diseases. CVS is generally considered safe. The study today, however, analyzes the entire body of research on CVS and suggests that the procedure may increase the rate of blood vessel malformations called hemangiomas. Hemangiomas are common blood vessel malformations that are caused by an abnormal growth of cells linking the blood vessels. They can appear as small birthmarks that sometimes disappear later in life or large malformations that need to be removed.
The lead author of the study, Dr. Lewis B. Holmes of Massachusetts General Hospital, says the findings suggest but do not prove that CVS may lead to hemangiomas or other vascular disruption birth defects, such as limb defects. Hemangiomas appear to be about three times more common in infants who undergo CVS. Limb defects may also be more common, especially defects of the fingers. One study found that defects affecting two fingers occurred in about 1 in 3,000 infants who had undergone CVS compared with about 1 in 54,000 who had not undergone CVS.
The way in which CVS may cause hemangiomas and other vascular disruptions is not clear although Holmes said it could be related to damage caused by bleeding from the placenta.
‘Women should certainly discuss this and other potential risks of CVS with their obstetrician,’ Dr. Mutaz B. Habal, editor-in-chief of the Journal of Craniofacial Surgery, said in a news release. ‘However, CVS is generally done for prenatal detection of serious genetic diseases like Down syndrome in pregnancies at high risk. The benefits of knowing the test results could outweigh the possible risk of hemangiomas or other abnormalities.’
-- Shari Roan