Definition of epigenetics and epigenetic traits

Summary

Epigenetics is the study of changes in gene expression that occur without altering the DNA sequence. These changes typically persist through cell division and affect how genes are regulated, influencing cellular and physiological traits. Epigenetic effects can arise from environmental factors or normal developmental processes, and they may be maintained for a cell’s lifetime or across multiple generations even though the underlying nucleotide sequence is unchanged. An epigenetic trait is commonly defined as a stably heritable phenotype produced by changes in a chromosome without alterations in the DNA sequence. While some definitions require heritability, others are broader and include stable but not necessarily heritable alterations in transcriptional potential. The term also refers to the mechanisms that create such traits, including DNA methylation, histone modifications, and regulation by non-coding RNAs, as well as other chromosome- and chromatin-related processes that can “register” and perpetuate altered gene activity states.

Key Points

• 1

  Epigenetics focuses on gene-expression changes that do not involve changes to the DNA nucleotide sequence, often persisting through cell division.

• 2

  An epigenetic trait is typically described as a stably heritable phenotype caused by chromosomal changes without DNA-sequence mutations, though broader definitions may include stable non-heritable changes.

• 3

  Major mechanisms include DNA methylation, histone modifications, and non-coding RNAs that regulate gene activity by altering chromatin and transcriptional states.