null mutation

genetics

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Last updated

July 16, 2026

Quick Summary

A "null mutation" in genetics is a mutation that results in a complete loss of function for a particular gene. This means that the gene product, typically a protein, is either not produced at all or is produced in a non-functional form.1

Mutations can arise from changes in the DNA sequence, such as point mutations where a single base pair is altered, or frameshift mutations involving the addition or deletion of bases. These alterations can lead to changes in the amino acid sequence of a protein, premature termination of protein synthesis, or complete absence of the protein.12

While most mutations occur spontaneously, factors like radiation and certain chemicals can increase their rate. The impact of a null mutation depends on the gene and the organism, but it fundamentally means the gene no longer performs its intended role.1

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heredity
Mechanisms of mutation
…gene is called a “null” mutation. Less-severe mutations are called “leaky” mutations because some normal function still “leaks through” into the phenotype.
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…gene is called a “null” mutation. Less-severe mutations are called “leaky” mutations because some normal function still “leaks through” into the phenotype.
Read More