Any of the covalently closed DNA molecules found in bacteria, many viruses, mitochondria, plastids, and plasmids. Small, polydisperse circular DNA's have also been observed in a number of eukaryotic organisms and are suggested to have homology with chromosomal DNA and the capacity to be inserted into, and excised from, chromosomal DNA. It is a fragment of DNA formed by a process of looping out and deletion, containing a constant region of the mu heavy chain and the 3'-part of the mu switch region. Circular DNA is a normal product of rearrangement among gene segments encoding the variable regions of immunoglobulin light and heavy chains, as well as the T-cell receptor. (Riger et al., Glossary of Genetics, 5th ed & Segen, Dictionary of Modern Medicine, 1992)

Descriptor ID	D004270
MeSH Number(s)	D13.444.308.283 G02.111.570.790.486.212 G05.360.580.156
Concept/Terms	DNA, Circular DNA, Circular Circular DNAs DNAs, Circular Circular DNA

Below are MeSH descriptors whose meaning is more general than "DNA, Circular".

Below are MeSH descriptors whose meaning is related to "DNA, Circular".

Below are MeSH descriptors whose meaning is more specific than "DNA, Circular".