In addition to findings that report continual spatio-temporal dynamics of gene expression across prenatal and postnatal developmental stages, there is evidence of fundamental differences between transcriptional programs at these distinct stages of development (Colantuoni, et al., 2011). It was shown that select fetal gene expression changes are negatively correlated with those occurring at postnatal stages of life. Thus, approximately 75% of the genes, that show a significant change in their expression in both the fetal and infant stages, reverse the direction of intra-stage expression dynamics between fetal and early postnatal life. And most of these reversals go from an increase of expression level in the prenatal period to a decrease in infancy. A second significant change in global gene expression in the developing brain, when a number of genes change the trajectory of their expression, occurs at the end of teenage stage of development–close to 20 years of age (Colantuoni, et al., 2011).
