Terry and colleagues analyzed DNA methylation profiles in leukocyte, or white blood cell, DNA in a multiethnic birth cohort from New York City (Terry et al., 2008). Multivariable models indicated that overall levels of DNA methylation were significantly associated with maternal smoking during pregnancy and a number of other covariates. Terry and coauthors point out that their data, if replicated in a larger number of samples, suggest that exposures experienced throughout the course of life – from fertilization onward – may be associated with DNA methylation in adulthood. Longitudinal studies capable of measuring within-individual changes in DNA methylation in a variety of tissues over time will yield important data informative of the intragenerational plasticity of DNA methylation.
