2.1.2. Insertions and Deletions (Indels)
Mutations involving situations where extra base pairs, ranging from one to thousands, are inserted into (insertion) or deleted from (deletion) the sequence of a gene are referred to as indels. Indels result in shifts in the reading frame of the gene with the rearrangement of the nucleotides into a completely new set of codons. This has grave consequences for protein synthesis as the amino acid sequences are manifestly different from the wild-type. Indels of one or two base pairs (or multiples) result in frameshifts while those of three base pairs (or multiples) are more innocuous as the reading frame tends to be preserved, i.e., the original triplet codons are not disturbed.