Indel (insertion-deletion) is a molecular biology term for an insertion or deletion of bases in the genome of an organism.
[1][2] In coding regions of the genome, unless the length of an indel is a multiple of 3, it will produce a frameshift mutation.
For example, a common microindel which results in a frameshift causes Bloom syndrome in the Jewish or Japanese population.
Indels can also be contrasted with Tandem Base Mutations (TBM), which may result from fundamentally different mechanisms.
[5] Indels, being either insertions, or deletions, can be used as genetic markers in natural populations, especially in phylogenetic studies.