There is a great degree of interest in better understanding the influences of maternal cigarette smoking during pregnancy on the brain and infant neurodevelopment; however, investigations considering epigenetic pathways are only beginning to emerge. Toledo-Rodriguez and colleagues investigated whether prenatal exposure to maternal cigarette smoking is associated with promoter methylation of brain-derived neurotrophic factor (BDNF) in blood samples from adolescents whose mothers smoked during pregnancy. BDNF, which is important for long-term memory, acts on certain neurons of the central nervous system and the peripheral nervous system, helping to support the survival of existing neurons, and encourage the growth and differentiation of new neurons and synapses (Huang & Reichardt, 2001). Toledo-Rodriguez and colleagues found that exposure to maternal cigarette smoking in utero is associated with a higher degree of DNA methylation in the BDNF exon 6 in adolescents whose mothers smoked during pregnancy, further suggesting that exposure to cigarette smoke while in utero may have long-term consequences still measurable into adolescence. The BDNF gene contains several exons, the expression of which is crucial for proper functioning of BDNF protein and which
