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Genes & Disease
What is a mutation?
A mutation is any change in the DNA sequence. Mutations can lead to genetic disorders or disease. Most mutations are recognised because the phenotype, that is the characteristics displayed by an organism, have changed. There are many different types of mutation. They can occur on a macroscopic level in the form of chromosomal mutations or they may be the result of a single base pair change in the DNA sequence. Mutations can occur within a gene preventing the synthesis of the correct protein, they may occur in gene promoter regions or in DNA regulatory regions changing the expression levels of the protein, or near the splice sites in introns causing disruption to the splicing process and production of an incorrect protein.
Mutations are rare events occurring at a rate of 1 in every 50 million bases added to the nucleotide chain. Most of the changes that happen are quickly repaired by our very efficient and accurate DNA repair system. However, this repair mechanism is not foolproof. Failure to repair all mutations has led to the introduction of some mutations that have made organisms fitter and better able to adapt to their environments. However, many mutations have detrimental effects for an organism and it is these mutations that are the basis of many human genetic disorders and disease.
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