Developmental dynamics of the epigenome: A longitudinal study of three toddlers

Epigenetic regulation plays an important role in development, at the embryonic stages and later during the lifespan. Some epigenetic marks are highly conserved throughout the lifespan whereas others are closely associated with specific age periods and/or particular environmental factors. Little is known about the dynamics of epigenetic regulation during childhood, especially during the period of rapid early development. Our study was aimed to determine whether the developmental program at the early stages of human development is accompanied by significant changes in the systems of genome regulation, specifically, by genome-wide changes in DNA methylation. Using a sequencing approach (MBD-seq) we investigated genome-wide DNA methylation patterns in the T-lymphocytes of three healthy toddlers at two timepoints within the second year of life. Pairwise comparison of the methylation patterns across the individuals and time points was conducted to determine common longitudinal changes in the DNA methylation patterns. Despite relatively high interindividual variability in their epigenetic profiles and the dynamics of these profiles during the second year of life, all children showed consistent changes in the DNA methylation patterns of genes involved in the control of the immune system and genes related to the development of the CNS. Thereby, we provide evidence that early development might be accompanied by epigenetic changes in specific functional groups of genes; many such epigenetic changes appear to be related to the rapid development of the CNS.