Glossary Term
Any transmissible change in the genetic material of an organism, which can result from radiation, viral infection, transposition, treatment with mutagenic chemicals and errors during DNA replication or meiosis. The effects of mutation range from single base changes to loss or gain of complete chromosomes. As many of the simpler alterations to DNA may be repaired, such changes are only heritable once the change is fixed in the DNA by the process of replication. Mutations may be associated with genetic diversity or with pathologies including cancer.
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Glossary Term
Drug-, radiation-induced, or spontaneous injuries to DNA that introduce deviations from its normal double-helical conformation. These changes include structural distortions that interfere with replication and transcription, as well as point mutations that disrupt base pairs and exert damaging effects on future generations through changes in DNA sequence. If the damage is minor, it can often be repaired (DNA repair); extensive damage can induce apoptosis.
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A mutation occurring within the protein-coding region of a gene which results in a shift in the reading frame of the encoded protein. Frameshift mutations often result in the premature truncation of a gene product.
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Any mutation that appears in the gametes and which will therefore be transmitted to the progeny with some frequency.
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A mutation class that includes insertion mutations, deletion mutations and mutation events where both an insertion and a deletion has occurred.
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A genetic variation where gain, loss, or exchange of DNA results in monoallelic loss of function mutations in a diploid cell. In the context of tumor suppressor genes, where a single copy is sufficient for functionality, loss of function for the second allele is associated with tumorigenesis.
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A point mutation occurring within the protein-coding region of a gene, and which codes for a different amino acid than expected.
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A point mutation occurring within the protein-coding region of a gene, and which codes for a stop that can truncate the protein.
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A small-scale mutation in which a single nucleotide is exchanged for another. Mutagenic chemicals and mistakes in DNA replication may result in point mutations.
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Nonfunctional DNA sequences that are very similar to the sequences of known genes. Many seem to have arisen as functional gene duplications that subsequently underwent mutation and loss of function. Others are structurally similar to mRNA and seem to have arisen by a reverse transcription event followed by integration into the genome. Some pseudogenes are transcribed and may play a role in regulation of its homologous gene.
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Glossary Term
A point mutation occurring within the protein-coding region of a gene, and which codes for the same amino acid as expected.
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Any mutation with an origin in cells that are not destined to become gametes. As a consequence, such mutations are not transmitted to progeny, though they will be transmitted during any mitosis within the individual. Somatic mutations may contribute to a broad variety of pathologies including cancer.
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