Circular RNAs are the predominant transcript isoform from hundreds of human genes in diverse cell types

PLoS One. 2012;7(2):e30733. doi: 10.1371/journal.pone.0030733. Epub 2012 Feb 1.


Most human pre-mRNAs are spliced into linear molecules that retain the exon order defined by the genomic sequence. By deep sequencing of RNA from a variety of normal and malignant human cells, we found RNA transcripts from many human genes in which the exons were arranged in a non-canonical order. Statistical estimates and biochemical assays provided strong evidence that a substantial fraction of the spliced transcripts from hundreds of genes are circular RNAs. Our results suggest that a non-canonical mode of RNA splicing, resulting in a circular RNA isoform, is a general feature of the gene expression program in human cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Exons
  • Gene Expression*
  • Humans
  • Protein Isoforms
  • RNA / genetics*
  • RNA Precursors / genetics*
  • RNA Splicing*
  • RNA, Circular


  • Protein Isoforms
  • RNA Precursors
  • RNA, Circular
  • RNA