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Small-scale mutations. 1  Point mutation â a change in one base in the DNA sequence. 2  Substitution â when one or more bases in the sequence is replaced by the same number of bases (for example, a cytosine substituted for an adenine).3  Inversion â when a segment of a chromosome is reversed end to end.arge-scale mutations. 1  Copy number variation (CNV) is a type of mutation where large chunks of DNA are inserted, repeated or lost. 2  These regions of DNA can be between 10,000 and 5,000,000 bases long. 3  Duplication of genes. 4  When there is an increase in the number of copies of a gene.
Mutations in these important types of genes may also occur in an individualâs germ cells â eggs or sperm. In these cases, a mutation can be passed on from one generation to the next. Such mutations â called germ line or heritable mutations â are often associated with hereditary cancer.This group includes genes such as BRCA1, a gene associated with hereditary breast and ovarian cancer. Oncogenes â Oncogenes promote cell proliferation and stop cell death, at times resulting in cancer. 2  Tumor suppressor genes â These protective genes normally limit the development and/or growth of tumors; when a tumor suppressor gene is mutated, it may fail to prevent a cancer from growing.