dCBE(hAICDA(starΔ)::Cas9(D10A)::NLS) is an artificial 'base editor' that can be used to irreversibly convert a single target cytosine DNA base in a programmable manner (using a guide RNA to direct the base editor to the target site), without requiring double-stranded cleavage of the DNA backbone or a donor template; it favors the conversion of C to T. dCBE(hAICDA(starΔ)::Cas9(D10A)::NLS) is composed of an optimized version of the cytidine deaminase encoded by the Homo sapiens AICDA gene (the nuclear export signal has been deleted and the optimized sequence contains amino acid substitutions K10E, T82I and E156G, see PMID:27798611) fused to the Cas9(D10A) nickase, with a Tag:NLS(SV40-largeT) nuclear localization signal at the C-terminal end of the fusion protein (FBrf0260443).