Table 1 Characteristics of ecDNA, eccDNA, neo and ring chromosome

ecDNA

1-3 Mb, visible under

microscope

Double

Oncogene amplification, regulatory regions, no centromeres or telomeres

Extrachromosomal DNA (double minutes)

BFB cycle, translocation-deletion-amplification, episome and chromothripsis

[1, 3]

eccDNA

 < 1 Mb. Invisible under microscope

Single or double

Small regulatory RNA

Extrachromosomal small circular DNA

Telomere circle, spcDNA, miDNA, episome

[93, 94]

Neo

chromosome

30–600 Mb, visible under microscope

Double

Contains centromere or telomere

Structurally abnormal chromosome

Chromothripsis and BFB cycles with telomere aggregation

[7, 9]

Ring chromosome

1.4–7.3 cms. Visible under microscope

Double

Circular or linear form, contains centromere and telomere

Breaks of telomeric ends, end-to-end fusion of the centric chromosome

End joining of DNA double-strand breaks, telomere_subtelomere junction, or rearrangement

[6]