InDel mutations - examples

Concept of a Reading Frame

Given a DNA sense strand that reads in the 5'3' direction, the corresponding polypeptide could be read as a series of triplets that starts at any of the first three nucleotides. These three possibilities are called Reading Frames. The sequence of bases in any one reading frames is sequential; the reading frames overlap.

In the example, the first reading frame starts with TCA, the second with CAT, and the third with ATA: each proceeds to the end of the sequence without interruption. Note that starting at the 4th nucleotide gives the same series as the 1st reading frame.