what is a missense mutation

A missense mutation is a type of DNA change that results in a different amino acid being encoded at a particular position in the resulting protein. It is a point mutation in which a single nucleotide change results in a codon that codes for a different amino acid. Missense mutations can be classified as deleterious mutations (disease-causing), normal variation (polymorphism or rare variant), or a "variant of uncertain significance". Missense mutations can alter the function of the resulting protein, and such mutations are responsible for human diseases such as Epidermolysis bullosa, sickle-cell disease, SOD1 mediated ALS, and a substantial number of cancers. However, in most cases, missense mutations do not affect the overall shape and function of the protein. Depending on which amino acid it codes for, missense mutations can be conservative (i.e., the resulting protein is functional) or nonconservative (i.e., the resulting protein is nonfunctional) .