Epigenetics: Regulation through repression

Epigenetics is the study of heritable changes in gene expression that occur without a change in DNA sequence. Epigenetic phenomena have major economic and medical relevance, and several, such as imprinting and paramutation, v iolate Mendelian principles. Recent discoveries Link the recognition of nuc leic acid sequence homology to the targeting of DNA methylation, chromosome remodeling, and RNA turnover. Although epigenetic mechanisms help to prote ct cells from parasitic elements, this defense can complicate the genetic m anipulation of plants and animals. Essential for normal development, epigen etic controls become misdirected in cancer cells and other human disease sy ndromes.