May 19, 2011 - Children whose mothers and grandmothers smoked during pregnancy are at an increased risk for asthma, but the underlying reasons for this are not well understood. A new study identified a process which occurs before birth called DNA methylation as the possible root cause. This process can alter the AXL gene, which plays an important role in many human cancers and in immune response, and these genes are passed from parent to child. The study used a detailed questionnaire to target 173 mothers and grandmothers of children with asthma and assess their smoking habits during pregnancy. The children who had been exposed to maternal smoking in utero had a 2.3% increase in DNA methylation of the AXL gene. The results indicate a need for further research on the effects that environmental factors have on changes in gene function or expression in early development. This is a largely unexplored area of research that could provide promising information on the relationship between exposure and disease.

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