CpG site | DNA sequence where a cytosine nucleotide is followed by a guanine nucleotide CpG is shorthand for 5′—C—phosphate—G—3′, that is, cytosine and guanine separated by only one phosphate group in the 5′ to 3′ direction The cytosine in CpG sites can be dynamically methylated and demethylated |
CpG island (CGI) | A CpG-dense region of DNA that often overlaps regulatory sequences Methylation of CpG islands can dynamically regulate gene expression, with decreased methylation often associated with increased expression |
Chromatin | DNA wrapped around histone core proteins for the purpose of tight packaging of DNA into a small volume to fit into the nucleus of a cell and protect the DNA structure and sequence |
Differentially methylated position | A single CpG site that is statistically significantly differentially methylated among study groups |
Differentially methylated region | A group of CpG sites across a region of DNA that is statistically significantly differentially methylated among study groups |
DNA methylation | DNA methylation is a process by which methyl groups are added to the DNA molecule Methylation can change transcriptional activity of a DNA segment without changing the sequence |
Enhancer | A region of DNA that binds to transcription factors, which then interact with promoter regions to upregulate gene expression |
Epigenome | Collection of epigenetic marks throughout the genome; genome-wide distribution of transcriptional regulators believed to mediate the memory of past cellular events |
Epigenome-wide association study (EWAS) | A study of the epigenome that looks for association between epigenetic variation and a high-level trait, such as disease status across individuals, or for association of a difference in organisation of a genomic regulator |
Genome-wide association study (GWAS) | A study that looks for association between genetic variation and a high-level trait such as disease across individuals, typically scanning millions of genetic variants genome-wide for association signals |
Histone modification | A histone modification is a covalent post-translational modification (PTM) to histone proteins The PTMs made to histones can impact gene expression by altering chromatin structure or recruiting histone modifiers |
Promoter | A region of DNA upstream of gene transcription start sites bound by RNA polymerase and transcription factors to facilitate gene expression |