What is a mutation?

• 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.

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