nonsense mutation


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sup·pres·sor mu·ta·tion

1. a second mutation that alters the anticodon in a tRNA so that it can recognize a nonsense (stop) codon, thus suppressing termination of the amino acid chain. Compare: amber mutation, ochre mutation, umber mutation.
2. genetic changes such that the effect of a m. in one place can be masked by a second m. in another location. There are two types: intergenic suppression (occurring in a different gene) and intragenic suppression (occurring in the same gene but at a different site).
Synonym(s): nonsense mutation

nonsense mutation

a mutation in which one of the three terminator codons in the mRNA used to signal the end of a polypeptide appears in the middle of a genetic message and causes premature termination of transcription and release of incomplete, generally nonfunctional polypeptides from the ribosome. The three types are amber mutation, ochre mutation, opal mutation.

nonsense mutation

A POINT MUTATION which changes a CODON that specifies an amino acid into a termination codon-one that marks the position where translation of a messenger RNA sequence should stop. The result is a gene with a segment lopped off. Such a gene will code for a protein that may have missing amino acids and may thus be functionally defective.

nonsense mutation

an alteration in a DNA POLYNUCLEOTIDE CHAIN that results in a NONSENSE CODON when transcribed on to mRNA.

mutation

1. a nucleotide change, including base substitutions, insertions or deletions in DNA, or RNA in the case of some viruses, that gives rise to the mutant phenotype.
2. an animal exhibiting such change. Called also a sport.

back mutation
see reverse mutation (below).
base substitution mutation
may be a transition in which a purine-pyrimidine pair is substituted by the other purine-pyrimidine pair, or transversion in which a purine-pyrimidine pair is replaced by one of the two pyrimidine pairs.
chain termination mutation
one in which the new base sequence introduces a stop codon and thereby prematurely terminates synthesis of the polypeptide; the three mutations are also called amber (UAG), ochre (UAA) and opal (UGA).
deletion mutation
one produced by loss of nucleotides from a DNA sequence.
frame shift mutation
occur as a result of either the insertion of a new base pair or the deletion of a base pair or a block of base pairs from the DNA base sequence; these, unless they occur in 3 or multiples of 3, are most serious in that the message to the right of the frame shift is garbled.
leaky mutation
one in which the amino acid substitution only partially disrupts the function of the protein; in bacteria this is usually manifested by reduced growth rate.
mis-sense mutation
one causing an amino acid substitution in the protein.
nonsense mutation
one in which a stop codon is substituted for a codon that specifies an amino acid.
operator constitutive mutation
one or more base changes in the operator region (originally defined for the lactose operon) which stop the repressor protein from tightly binding to sequence such that it is less effective in preventing RNA polymerase from inhibiting transcription.
point mutation
a single changed base pair in the DNA of an organism which may be a base substitution, base insertion or base deletion.
mutation rate
the frequency of mutations in the population over time.
repressor-constitutive mutation
in regulation of gene expression, a mutation in the repressor protein that decreases the binding affinity of the repressor protein for the operator which leaves the gene permanently turned on.
reverse mutation
one in which the wild-type phenotype is restored; such organisms are called revertants. Called also back mutation, reversion mutation.
second-site mutation
see suppressor mutation.
silent mutation
one in which there is a base change but because of the redundancy of the genetic code the same amino acid is coded, or one in which there is an amino acid substitution in the protein which has no detectable effect on the phenotype.
somatic mutation
a change in the DNA sequence that occurs in somatic cells, i.e. not gametes. The mechanism underlying the generation of diversity of antigen recognition by immunoglobulins and T cell receptor molecules. The fundamental cause of cancer, in which the mutation occurs spontaneously or is induced by carcinogens, such as sunlight, chemicals or viruses.
suppressor mutation
a particular type of reversion mutation in which a mutation at a second site restores the original phenotype; most simply a mutation produced by a base deletion may be restored to wild type by a proximate but independent base substitution. Called also second-site mutation.
temperature-sensitive (ts) mutation
one in which there is an altered protein that is active at one temperature, typically 86°F (30°C) and inactive at a higher temperature, usually 104 to 108°F (40 to 42°C), e.g. ts mutant virus and bacteria.
transdominant mutation
occur in genes producing diffusible products, in contrast to cis-dominant mutation in which mutations occur in regulatory sequences that are recognized by other proteins.
transition mutation
one in which the base change does not change the pyrimidine-purine orientation. See also base substitution mutation (above).
transposition mutation
one produced by the insertion of a transposable genetic element.
transversion mutation
one in which the purine-pyrimidine orientation is changed to pyrimidine-purine or vice versa. See also base substitution mutation (above).
References in periodicals archive ?
The third novel mutation we identified is a heterozygous nonsense mutation in POMC exon 3 that encodes a truncated [beta]-endorphin peptide at codon 244.
15 October 2010 - US biopharmaceutical company PTC Therapeutics Inc said today that final analyses of Phase IIb efficacy data suggest ataluren slowed the loss of walking ability in patients with nonsense mutation dystrophinopathy, a disease continuum comprising Duchenne and Becker muscular dystrophy (nmDBMD).
Study candidates include patients who are at least six years of age and have CF due to a nonsense mutation.
Mutated endoglin proteins do not appear to be produced at the cell surface, and some nonsense mutations give rise to undetectable mRNA transcripts (3, 20, 21), leading to a loss of protein production.
Nonsense mutation in MERTK causes autosomal recessive retinitis pigmentosa in a consanguineous Pakistani family.
Food and Drug Administration (FDA) for the New Drug Application (NDA) of the investigational medicine ataluren for the treatment of nonsense mutation dystrophinopathies.
M2 PHARMA-October 26, 2017-FDA Fails to Approve PTC Therapeutics NDA for Ataluren for Nonsense Mutation Dystrophinopathies
The biological sense of maintaining high-energy-consuming genome regions rich in G+C nucleotides is explained in the reduced risk of nonsense mutation.
If the unexpected mutation is something like a frameshift or nonsense mutation, accepting this as the cause behind the symptoms may be relatively straightforward; if it's a missense mutation where one amino acid code is substituted for another, interpretation may be more complex and require evaluation of the encountered mutation in a model system to ascertain if it's causal.
R161X mutation identified in the family in the present study is a nonsense mutation described previously in the literature.
Nonsense mutation and inactivation of SMARCA4 (BRG1) in an atypical teratoid/rhabdoid tumor showing retained SMARCB1 (INI1) expression.