The protein is shorter than usual and does not contain all the amino acids that it should. Therefore, this protein is most likely nonfunctional. Frameshift Mutations Another type of mutation is a frameshift mutation which is caused by the insertion or a deletion of a base pair. An inserted or deleted nucleotide alters the triplet grouping of nucleotides into codons and shifts the reading frame so that all nucleotides downstream from the mutation will be improperly grouped.