It is vital to know that a protein's function is dependent on its structure.

Any mutation that alters a protein's structure can create consequences for protein function, with the potential of having large impacts on the survival of the organism. Mutations can thus be categorised as neutral, deleterious, or beneficial mutations. Neutral mutations result in an unchanged protein product (in the case of a synonymous mutation), so therefore the organism's survival is unaffected. Missense substitutions can also be neutral, given that the original amino acid is interchanged with another that has similar properties to its previous amino acid. Deleterious mutations disrupt the function of proteins, which decreases the organism's ability to survive and function normally. Nonsense mutations are usually deleterious as they result in the production of a non-functional, incomplete protein. It's important to note that most mutations are deleterious. On certain occasions, gene mutations have the possibility of producing a new allele which actually benefits the survival of the organism. For example, it may be a missense mutation that changes the function of the original protein, or perhaps a nonsense mutation that eliminates a harmful protein. It's important to note that these mutations are uncommon.