TP53 and cancer: CpG dinucleotides are known to be preferred sites of UV mutation due to CPD formation, particularly at methylated CpG sites within cancer genes such as TP53. These C and 5-methylcytosine (5mC) residues can also spontaneously deaminate to uracil and thymine, respectively, which, if not repaired, will result in C > T/G > A transitions34,35.