Maternal folic acid supplementation and risk of autism: Reply

摘要

Folate is a vital co-factor in DNA synthesis, DNA repair, and DNA methylation, and there are multiple ways in which fetal brain development could potentially be influenced by a lack of folate or a reduced ability to use available folate. Consequently, the analytic approach has to be broad and include both genetic and epigenetic analyses, as well as analyses of folate and other related metabolites in blood plasma. Our study was purely epidemiological and did not include data on biological parameters, which is why we were not able to investigate the biological underpinnings of our findings. We found a reduced risk of autism spectrum disorders in children whose mothers had taken folic acid around the time of conception and during early pregnancy, at a time when the fetus does not have any metabolism or immune function of its own. If aberrant folate metabolism, folate receptor autoantibodies, or both were to explain our findings, those biological mechanisms would have to be operating in the mothers, who in most cases are perfectly healthy and do not have autism spectrum disorders. The abnormalities referred to by Vahabzadeh and McDougle have only been demonstrated in children with autism spectrum disorders.