Identical DNA sequences can produce different outcomes. Epigenetics studies heritable changes in gene expression that do not involve alterations to the underlying DNA sequence. Chemical modifications to DNA and histone proteins, along with non-coding RNAs, regulate whether genes are active or silent.

DNA methylation and histone modification are the best-characterized mechanisms. These marks are established during development and can respond to environment, diet, and stress. Some epigenetic states persist through cell division and, in certain cases, across generations.

Epigenetic dysregulation contributes to cancer, imprinting disorders, and complex diseases. Researchers map these marks genome-wide to understand development and disease. Unlike DNA mutations, many epigenetic changes are potentially reversible, opening therapeutic possibilities with drugs that alter methylation or histone acetylation.

• Heritable changes in gene expression without DNA sequence change
• Involves DNA methylation and histone marks
• Responds to environmental influences
• Relevant to development and disease