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Missense mutations in the MeCP2 protein can cause Rett syndrome, otherwise known as the RTT phenotype [7]. T158M, R306C and R133C are the most common missense mutations causing RTT [7]. T158M is a mutation of an adenine being substituted for a guanine causing the threonine at amino acid position 158 being substituted with a methionine [8].
Nonsense mutations are nonsynonymous substitutions that arise when a mutation in the DNA sequence causes a protein to terminate prematurely by changing the original amino acid to a stop codon. Another type of mutation that deals with stop codons is known as a nonstop mutation or readthrough mutation, which occurs when a stop codon is exchanged ...
Site-directed mutagenesis is a technique often employed to create knock-in and knock-out models that express missense mRNAs. For example, in knock-in studies, human orthologs are identified in model organisms to introduce missense mutations, [7] or a human gene with a substitution mutation is integrated into the genome of the model organism. [8]
The human germline mutation rate is approximately 0.5×10 −9 per basepair per year. [1] In genetics, the mutation rate is the frequency of new mutations in a single gene, nucleotide sequence, or organism over time. [2] Mutation rates are not constant and are not limited to a single type of mutation; there are many different types of mutations.
Nonsense mutations comprise around 20% of single nucleotide substitutions within protein coding sequences that result in human disease. [12] Nonsense mutation-mediated pathology is often attributed to reduced amounts of full-length protein, because only 5-25% of transcripts possessing nonsense mutations do not undergo nonsense-mediated decay (NMD).
On the other hand, if a missense mutation occurs in an amino acid codon that results in the use of a different, but chemically similar, amino acid, then sometimes little or no change is rendered in the protein. For example, a change from AAA to AGA will encode arginine, a chemically similar molecule to the intended lysine.
A missense mutation means the nucleotide mutation alters the overall codon triplet such that a different amino acid is paired with the new codon. In the case of sickle cell anemia, the most common missense mutation is a single nucleotide mutation from thymine to adenine in the hemoglobin B subunit gene. [23]
Missense mutations code for a different amino acid. A missense mutation changes a codon so that a different protein is created, a non-synonymous change. [4] Conservative mutations result in an amino acid change. However, the properties of the amino acid remain the same (e.g., hydrophobic, hydrophilic, etc.).