An apyrimidinic site is created when uracil is removed from the site by the enzyme uracil DNA N-glycosidase. DNA replication errors that are overlooked during proofreading or fail to be repaired can result in mutations. One category of genetic mutations resulting from replication errors are the triplet repeat diseases.he insertion of an incorrect base or an additional base during DNA replication occurs when bases are misread during the process. Insertions and substitutions are caused by spontaneous chemical changes to the DNA structure.