What are the different forms of DNA damage; depurination, deamination and alkylation?

Depurination: removal of the purine base (either guanine or adenine) of DNA deamination: the removal of the amino group of the DNA base alkylation: the addition of an alkyl group to the DNA, which has implications for DNA pairing (this the not the same as methylation, in which methyl groups are added to the sugar backbone of the DNA)