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

From: Small ring has big potential: insights into extrachromosomal DNA in cancer

  Size Single/double strand Sequence feature Definition Origination Refs.
ecDNA 1-3 Mb, visible under
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]
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]