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 2021-05-05


Genomics Live!
Cancer Research:
The Big Questions
with Dr Alastair Droop

We'll be joined by Alastair Droop to discuss how artificial intelligence is being used in cancer and health care, and the ethics of AI.

Date: Thursday 13th May 4:30-5:30pm GMT | Register at Eventbrite