nonsense mutation


Also found in: Dictionary, Thesaurus, Legal, Encyclopedia, Wikipedia.

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 ?
Translarna is an oral protein restoration therapy that has the potential to benefit patients with genetic disorders caused by a nonsense mutation.
The positive opinion from the CHMP recommending the conditional approval of Translarna in nonsense mutation Duchenne muscular dystrophy is a major milestone for the DMD community and we are extremely proud of this joint achievement in accelerating the access to Translarna for patients with nonsense mutation DMD," stated Stuart W.
NASDAQ: PTCT), today announced that the European Medicines Agency (EMA) has validated the submission of a variation for a new indication for Translarna(TM) (ataluren) for the treatment of nonsense mutation cystic fibrosis (nmCF) for patients not taking chronic inhaled aminoglycoside antibiotics.
PTC) today announced that PTC124, the company's orally delivered investigational new drug for the treatment of genetic disorders due to nonsense mutations, was featured in a symposium at Myology 2008, the Third Annual Congress of Myology, on Friday, May 30 in Marseilles.
Congenital hypothyroidism due to mutations in the sodium/ iodide symporter: identification of a nonsense mutation producing a downstream cryptic 3' splice site.
Patient 56 harbored a c54C>A transversion originating the nonsense mutation Ser185X (TGC changes to stop codon TGA), which predicts a truncated protein consisting of only 185 amino acids.
Pipeline analysis: comprehensive data split across different phases, emerging trends and mechanisms of action under development, including nonsense mutation readthrough inducer, exon-skipping therapies, synthetic electron transporter, PDE5 inhibitor.
However, as Mahadevan and Benson (2) point out, a nonsense mutation at this position could have clinical consequences different from those of the Leiden mutation.
We are also planning to submit an application for Translarna to treat nonsense mutation cystic fibrosis to the European Medicines Agency by the end of this year.
Case 3 carried a novel POMC heterozygous nonsense mutation that introduces a stop codon in the [beta]-endorphin peptide (E244X) and the above-described 9-bp insertion (AGC AGC CGC, S-S-G) between codons 93 and 99 in homozygosity.
Expected Trial Results and Planned Commercial Launch - On Operational front, the Company highlighted that it aims to release the top-line data from its ongoing Phase 3 ACT DMD trial by Q4 2015 and it expects the results to form the basis for finalizing its New Drug Application for the approval of Translarna in nonsense mutation DMD.