Basic concepts of epigenetics
Epigenetic mechanisms maintain mitotically heritable differences in gene expression potential without altering the primary DNA sequence. This review highlights epigenetic mechanisms that are relevant to normal and abnormal human developmental and differentiation processes.
Michal Inbar-Feigenberg, M.D., Sanaa Choufani, Ph.D., Darci T. Butcher, Ph.D., Maian Roifman, M.D., Rosanna Weksberg, M.D., Ph.D.
Volume 99, Issue 3, Pages 607-615, 1 March 2013
Several types of epigenetic marks facilitate the complex patterning required for normal human development. These epigenetic marks include DNA methylation at CpG dinucleotides, covalent modifications of histone proteins and non-coding RNAs. They function in a highly orchestrated manner, regulating mitotically heritable differences in gene expression potential without altering the primary DNA sequence. In germ cells and the developing embryo, genomewide epigenetic reprogramming drives the erasure and reestablishment of correct epigenetic patterns at critical developmental time periods and in specific cell types. Two specific types of epigenetic regulation established in early development include X chromosome inactivation and genomic imprinting; they regulate gene expression in a dosage-dependent and parent of originspecific manner, respectively. Both genetic and environmental factors impact epigenetic marks, generating phenotypic variation that ranges from normal variation to human disease. Aberrant epigenetic patterning can lead to a variety of human disorders, including subfertility and imprinting disorders.