A nonsense mutation is a change in the polynucleotide sequence that results in the production of a protein chain terminating codon that prematurely stops protein synthesis during the process of translation. As a result of a nonsense mutation, instead of the insertion of the proper amino acid into the chain of amino acids bonded together to form a protein, the synthesis of the protein prematurely stops. Unless there is another mutation in a gene that codes for a transfer RNA (tRNA) that allows the suppression of a nonsense mutation, a premature termination of protein synthesis results in the manufacture and release of an incomplete (truncated) and usually nonfunctional protein fragment.

A mutation is a change in a gene or chromosome. There are many types of mutations, including those resulting in a substitution of bases in the DNA sequence (i.e., one nucleotide is exchanged for another...