Summary
Insertion or deletion of nucleotides not in multiples of three that shifts the reading frame of the codons.
In depth
Adding or removing one or two bases shifts the codon grouping and changes every downstream amino acid, usually leading to an early stop codon and a nonfunctional protein. Insertions or deletions in multiples of three preserve the frame but add or remove amino acids.
Frameshifts are generally more damaging than substitutions.
Insertions or deletions in multiples of three bases keep the frame and add or remove whole amino acids (such as the common CFTR delta F508 deletion of three bases). Others, such as a single base deletion, shift the reading frame and nearly always cause truncated, unstable products.
Frameshifts underlie a common Tay-Sachs allele (a four-base insertion in HEXA) and many cases of Duchenne muscular dystrophy; the latter is treated experimentally by exon skipping, which restores the frame so that a shortened but partly working dystrophin is made.
Example: reading the sentence THE FAT CAT ATE THE RAT, deleting the first E gives THF ATC ATA TET HER AT, which is nonsense.
Frequently asked questions
What is Frameshift Mutation?
Insertion or deletion of nucleotides not in multiples of three that shifts the reading frame of the codons.
Which area of biology covers Frameshift Mutation, and how advanced is it?
Frameshift Mutation is one of the 54 topics in Genetics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Point Mutations, Allele, Trinucleotide Repeat Disorders.
Can you give an example of Frameshift Mutation?
Tay-Sachs disease is often caused by a 4-base insertion in the HEXA gene.
What should I learn before Frameshift Mutation?
Work through the Beginner topics in Genetics first, such as Heredity, Gene, Allele, then return to Frameshift Mutation. Intermediate topics assume the Beginner vocabulary.
What topics are related to Frameshift Mutation?
The closest topics to Frameshift Mutation are Point Mutations, Allele, Trinucleotide Repeat Disorders, Mutations. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Frameshift Mutation?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Frameshift Mutation. To practise the whole of Genetics, use the Genetics quiz.
How is Frameshift Mutation different from Point Mutations?
Frameshift Mutation: Insertion or deletion of nucleotides not in multiples of three that shifts the reading frame of the codons. Point Mutations: Changes to a single nucleotide, classed as silent, missense or nonsense depending on the effect on the protein. Read both side by side and note what each one explains.
How should I study Frameshift Mutation step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Point Mutations and explain the difference aloud. Finally, take the Genetics quiz and come back to this page for any question you miss.