Definition Of 'Epigenetics' Clarified

The definition is intended to address confusion within the scientific community about the distinction between the mechanisms of epigenetic memory during early development versus those of dynamic chromatin regulation involved in differential expression of genes throughout adult life. The mechanisms underlying epigenetic memory are of great importance to human development and disease, but they are poorly understood.

The proposed definition reads: “an epigenetic trait is a stably inherited phenotype resulting from changes in a chromosome without alterations in the DNA sequence.” Shilatifard and colleagues have also proposed three categories of signals that operate in the establishment of a stably heritable epigenetic state. The first is a signal from the environment, the second is a responding signal in the cell that specifies the affected chromosomal location, and the third is a sustaining signal that perpetuates the chromatin change in subsequent generations.

“The field of ‘epigenetics’ has been an exciting one and has grown swiftly over the past several years, extending well beyond an initial discovery phase and identification of fundamental non-genetic and chromatin-based regulatory mechanisms,” said Dr. Shilatifard. “This collective effort to define and discuss ‘epigenetics’ is an attempt to add focus and clarity to this exciting and growing area of research.”

Dr. Shilatifard’s publication appeared April 1 in Genes and Development and resulted from a meeting on December 7-10, 2008 that he co-organized at Cold Spring Harbor Laboratory in New York to discuss aspects of epigenetic control in genomic function and to develop a consensus definition of “epigenetics” for consideration by the broader research community.