Mutation is a change in a genome.

Classification of mutations

What types of mutations are there?

  • Large scale mutations (chromosome abnormalities):
    • polyploidy: sets of chromosomes are duplicated
    • amplifications or gene duplications
    • deletions: loss of entire chromosomal regions
    • chromosomal rearrangements:
      • inversions
      • translocations
    • loss of heterozygosity: in diploid cells, we have two copies of each gene, somewhat different as inherited from parents; if we lose one, this is different from homozygosity which means identical two copies of a gene.
  • Small scale mutations:
    • insertions of nucleotides; results in frameshift
    • deletions
    • substitutions
      • synonymous (same amino acid encoded)
      • non-synonymous
        • missense (different amino acid encoded)
        • nonsense (premature termination)

Consequences of mutations for cancer

  • mutations that cause uncontrolled growth and multiplication of cells
  • and other mutations that block the normal defenses that protect against unnatural growth.

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