A form of point mutation resulting in a nonsense codon that does not code for an amino acid and leads to a protein product that is early truncated.
In nonsense mutations, the protein product from a sequence of DNA with a nonsense mutation is prematurely truncated, incomplete and often nonfunctional. Genetic disease such as Duchenne muscular dystrophy is caused by a nonsense mutation in gene responsible for a specific protein, for example, dystrophin.
Compare: missense mutation, silent mutation.
See also: point mutation