What type of mutation commonly affects cpg islands, altering promoter regions of mammalian genes?

The CG Island refers to a brief stretch of DNA in which the frequency of the CG sequence is greater in comparison to other regions. It is also known as the CpG Island, where p basically indicates that C and G are associated with a phosphodiester bond.

Deamination is a mutation that usually influences CpG islands. Deamination refers to the withdrawal of an amino group from a molecule.