Editing Expectations Although genetic information is stored in DNA, and faithfully copied into RNA, the cell can make the odd (and occasionally vitally important) change to the meaning of code during a process known as RNA editing. Thirteen edited genes are known in the nonrepetitive portion of the human genome, but the overall prevalence of RNA editing is unclear. Li et al. (p. 1210 ), used an unbiased genome-wide approach to identify 239 sites (in 207 target genes), with stringent criteria for editing. The sites identified included 10 of the 13 known edited genes. Fourteen out of 18 randomly chosen sites were validated by sequencing, and these putatively edited genes were enriched for synapse, cell trafficking, and membrane functions. Furthermore, lowering the search stringency suggested that many more human genes may be edited at lower frequencies.

Genome-Wide Identification of Human RNA Editing Sites by Parallel DNA Capturing and Sequencing