Gene, Smoking Link Established In Cleft Palates By Lisbeth Pettingill Even before a woman knows she is pregnant, her smoking can trigger a specific gene in the unborn baby to produce a common birth defect, isolated cleft palate, according to a recent study by researchers at the Johns Hopkins University School of Public Health. The genotype itself appears in approximately 13.5 percent of the population. Their study, published in the April 1 issue of the "American Journal of Epidemiology," showed a significant association between the baby's genotype for a particular growth factor (transforming growth factor alpha, or TGFA) and risk of cleft palate (where the roof of the mouth does not close properly during early fetal development) when the mother smoked. Babies of mothers who did not smoke showed no difference in risk whether they carried the gene or not. "This is the first evidence that women who smoke are also placing their unborn children at risk based on the baby's genes," said Terri Beaty, professor of epidemiology at the School of Public Health and senior author of the study. "Since this birth defect occurs very early in pregnancy and since it is the baby's genes that determine risk, this is one more reason for all women of reproductive age to avoid smoking," she added. The study involved infants with isolated birth defects, consisting of 69 cleft palate-only cases, 114 cleft lip with- or without-palate cases and 284 controls with non-cleft birth defects, all born in Maryland from 1984 to 1992. Data for the study came from the Birth Defects Reporting and Information System operated by the Division of Hereditary Disorders of the Maryland Department of Health and Mental Hygiene. Oral clefts, including cleft palates, are among the most common birth defects, averaging one per 1,000 live births among Caucasians. Most cases occur as isolated birth defects.
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