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Mutation is a change in a gene or chromosome. It is a rare, random change in the genetic material, and in some cases it can be inherited.

Causes of mutation

Mutation can be spontaneous. It just happens, or it can happen because of:

• ionising radiation
• chemical mutagens – such as tar from cigarette smoke

Ionising radiation includes gamma rays, X-rays, and ultraviolet rays. The greater the dose of radiation a cell gets, the greater the chance of mutation.

Effects of mutation

A mutation may be neutral and have no effect. For example, the protein that a mutated gene produces may work just as well as the protein from the normal gene.

A mutation may sometimes be beneficial. For example, people who are carriers (heterozygous) for the sickle cell allele are more resistant to malaria (a tropical disease) than people who do not have the mutated gene.

Some mutations can be harmful. A change in the gene might produce a faulty or non-functioning protein, resulting in a genetic disease, such as cystic fibrosis.