Which mutations can lead to a frameshift in the genetic sequence?

A frameshift mutation occurs when the number of nucleotides inserted into or deleted from the genetic sequence is not a multiple of three. This disruption of the reading frame alters the grouping of codons and typically leads to the production of a completely different set of amino acids from that point onward in the protein synthesis process. This can have significant consequences for the structure and function of the resulting protein.

Insertion or deletion mutations directly change the length of the sequence, which shifts the reading frame for the entire downstream sequence of codons. If one or two nucleotides are inserted or deleted, all subsequent amino acids in the protein are affected, which is why these mutations are classified as frameshift mutations.

In contrast, point mutations and substitution mutations typically involve changes to a single nucleotide without altering the overall number of nucleotides in the sequence, thereby not causing a frameshift. Chromosomal mutations may involve larger-scale changes, such as duplications or translocations, but do not directly account for the frameshift at the level of individual codons unless they also involve insertions or deletions at a smaller scale.