Prenatal test may raise birthmark risk

NEW YORK Mon Jan 5, 2009 10:35am EST

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NEW YORK (Reuters Health) - A test performed in early pregnancy to check for genetic defects such as Down's syndrome in the fetus appears to be linked to increased chances that the baby will be born with a birthmark, or "infantile hemangioma," researchers report.

Chorionic villus sampling or CVS involves using a needle to collect samples of the embryonic structure that goes on to form the placenta. The process can be performed as early as 10 weeks into pregnancy, and provides cells of fetal origin that can be examined for chromosomal abnormalities.

Because several reports published in the 1990s suggested that there were occasional fetal effects from CVS, Dr. Lewis B. Holmes reviewed published studies to see if the procedure might be linked to infantile hemangiomas and possibly limb defects.

"Only a few studies have been conducted on the occurrence of hemangiomas in CVS-exposed infants," Holmes, of Massachusetts General Hospital for Children, Boston, emphasizes in his article in the Journal of Craniofacial Surgery.

In one study, Holmes reports, researchers found "cavernous or strawberry hemangiomas" in 12 of 95 (12.6 percent) CVS-exposed infants compared with 3 of 87 (3.4 percent) infants who had been exposed to amniocentesis, which is typically performed later in pregnancy.

In another study, hemangiomas were seen in 21.1 percent in 578 CVS-exposed infants versus 7.4 percent in 445 amniocentesis-exposed infants. Some babies in the CVS group, but none in the amniocentesis group, had multiple hemangiomas.

Holmes also looked at the evidence for an association between CVS and birth defects involving the limbs, especially the fingers, and found some "clear" correlations. The evidence suggests that these risks are greater when CVS is performed earlier in pregnancy, such as at 8 to 9 weeks gestation.

One large study, Holmes reports, found that the underdevelopment or absence of any two fingers occurred in 1 of 3,372 CVS-exposed infants compared to 1 of 53,751 unexposed infants.

Furthermore, a multi-state study from 1988 through 1992 showed that limb defects were "six times more common in CVS-exposed infants in comparison to the unexposed," he notes.

Nonetheless, because CVS detects serious genetic diseases like Down's syndrome, "the benefits of knowing the test results could outweigh the possible risk of hemangiomas or other abnormalities," the editor-in-chief of the journal points out in a written statement.

SOURCE: Journal of Craniofacial Surgery, December 2008.

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