During transcription, each triplet of nucleotides o 'codon' specifies a particular amino acid. A frameshift mutation is any alteration in the DNA sequence caused by a deletion or insertion (collectively referred to as indels) that shifts the manner the messenger RNA (mRNA) sequence is read during translation. In this example, the frameshift mutation occurred at the 74th nucleotide base, this means that the remaining 38 nucleotides will be out of the original frame (112 - 74 = 38 bases), thereby 13 codons will be out-of-frame (38/3 = 12.6 >> 13 codons), so 13 of the amino acids will be affected by this mutation.
