Mutations are changes to the genetic code. Mutations can either be inherited from a parent (germline) or acquired throughout one's lifetime (somatic). Somatic and germline mutations can both be responsible for alterations in the genome that lead to cancer formation. Only germline mutations can be passed on to offspring. Many physical and chemical agents cause mutations in DNA that can lead to cancer. These agents are considered carcinogenic (cancer-causing).
Mutations can be as small as a single nucleotide change referred to as a single nucleotide polymorphism (SNP) or as large as an entire section of a chromosome being rearranged, deleted, or duplicated. Small changes such as SNPs may have no impact on the structure of the protein. Chromosome deletions and rearrangements can affect multiple genes.
