A missense mutation is a change in DNA that swaps one amino acid in a protein for a different one. This can have little effect, or it can change how the protein works.

Quick Scoop

In simple terms, DNA is read in groups of three bases called codons. If one base changes and the codon now codes for a different amino acid, that is a missense mutation.

Why it matters

  • Some missense mutations are harmless and do not noticeably affect the protein.
  • Others can alter the protein’s shape or function and contribute to disease.
  • A well-known example is sickle-cell disease , which involves a missense mutation in the gene for hemoglobin.

Simple example

If a codon originally tells the cell to place one amino acid, but a single DNA letter change makes it place a different one, the protein sequence changes. That single swap is the key idea behind a missense mutation.

TL;DR: A missense mutation is a one-letter DNA change that causes one amino acid in a protein to be replaced by another.