Luckily, off-target edits made by CRISPR, like other gene-editing technologies, tend to be fairly predictable, since they affect only the DNA sequences that are most similar to the matching guide RNA. If CRISPR is programmed to target a twenty-letter sequence in gene X, but gene Y has a similar DNA sequence that differs in only one letter, there is a finite probability that CRISPR will introduce edits in both genes. The less closely the two sequences mirror each other, the lower the likelihood of off-target mutations.
