Susan *† and Steven Henikoff‡ *Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142; and ‡The Fred Hutchinson Cancer Research Center, Seattle, WA 98109 Over the past half-century, the central dogma, in which DNA makes RNA makes protein, has dominated thinking in biology, with continuing refinements in understanding of DNA inheritance, gene expression, and macromolecular interactions. However, we have also witnessed the elucidation of epigenetic phenomena that violate conventional notions of inheritance. Protein-only inheritance involves the transmission of phenotypes by self-perpetuating changes in protein conformation. Proteins that constitute chromatin can also transmit heritable information, for example, via posttranslational modifications of histones
