Mutations are changes to the genetic code. They 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, but 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 like SNPs may not impact the protein's structure, but chromosome deletions and rearrangements can affect multiple genes.
