AICDA and neoplasm: Cytosine, for example, can be deaminated by activation-induced cytidine deaminase/apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like (AID/APOBEC) family enzymes, leading to the formation of uracil [1], potentially leading to a C-to-T transition—a common spontaneous mutation found in human tumour cells [2].