What is a mutation?

A mutation is a change that occurs in our DNA sequence, either due to mistakes when the DNA is copied or as the result of environmental factors such as UV light and cigarette smoke. 

  • Over a lifetime our DNA can undergo changes or ‘mutations’ in the sequence of bases, A, C, G and T.
  • This results in changes in the proteins that are made. This can be a bad or a good thing.
  • Mutations can occur during DNA replication if errors are made and not corrected in time.
  • Mutations can also occur as the result of exposure to environmental factors such as smoking, sunlight and radiation.
  • Often cells can recognise any potentially mutation-causing damage and repair it before it becomes a fixed mutation.
  • Mutations contribute to genetic variation within species.  
  • Mutations can also be inherited, particularly if they have a positive effect.
  • For example, the disorder sickle cell anaemia is caused by a mutation in the gene that instructs the building of a protein called haemoglobin. This causes the red blood cells to become an abnormal, rigid, sickle shape. However, in African populations, having this mutation also protects against malaria.
  • However, mutation can also disrupt normal gene activity and cause diseases, like cancer
  • Cancer is the most common human genetic disease; it is caused by mutations occurring in a number of growth-controlling genes. Sometimes faulty, cancer-causing genes can exist from birth, increasing a person’s chance of getting cancer. 
Illustration showing an example of a DNA mutation. Image credit: Genome Research Limited

An illustration to show an example of a DNA mutation.
Image credit: Genome Research Limited


This page was last updated on 2021-07-21