Differentially methylated regions (DMRs) are

genomic Genomics is an interdisciplinary field of biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes as well as its hierarchical, three-dim ...

regions with different

DNA methylation DNA methylation is a biological process by which methyl groups are added to the DNA molecule. Methylation can change the activity of a DNA segment without changing the sequence. When located in a gene promoter, DNA methylation typically acts t ...

status across different biological samples and regarded as possible functional regions involved in gene transcriptional regulation. The biological samples can be different cells/tissues within the same individual, the same cell/tissue at different times, cells/tissues from different individuals, even different alleles in the same cell. DNA is mostly methylated at a

CpG site The CpG sites or CG sites are regions of DNA where a cytosine nucleotide is followed by a guanine nucleotide in the linear sequence of bases along its 5' → 3' direction. CpG sites occur with high frequency in genomic regions called CpG isl ...

, which is a

cytosine Cytosine () ( symbol C or Cyt) is one of the four nucleobases found in DNA and RNA, along with adenine, guanine, and thymine (uracil in RNA). It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached (an am ...

followed by a

guanine Guanine () ( symbol G or Gua) is one of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine (uracil in RNA). In DNA, guanine is paired with cytosine. The guanine nucleoside is called ...

. The “p” refers to the phosphate linker between them. DMR usually involves adjacent sites or a group of sites close together that have different methylation patterns between samples.

CpG islands The CpG sites or CG sites are regions of DNA where a cytosine nucleotide is followed by a guanine nucleotide in the linear sequence of bases along its 5' → 3' direction. CpG sites occur with high frequency in genomic regions called CpG isl ...

appear to be unmethylated in most of the normal tissues, however, are highly methylated in cancer tissues. There are several different types of DMRs. These include tissue-specific DMR (tDMR), cancer-specific DMR (cDMR), development stages (dDMRs), reprogramming-specific DMR (rDMR), allele-specific DMR (AMR), and aging-specific DMR (aDMR). DNA methylation is associated with

cell differentiation Cellular differentiation is the process in which a stem cell alters from one type to a differentiated one. Usually, the cell changes to a more specialized type. Differentiation happens multiple times during the development of a multicellula ...

and proliferation.

References

{{Reflist Epigenetics