Changes in DNA in a (protein-coding) exon that don’t change the resultant protein sequence due to redundancy in the genetic code (different codon spellings for the same amino acid). They are often, but not always, silent. They may affect expression of the protein-when, where, & how much protein’s made. Classification is based on whether they change a corresponding protein sequence. The opposite are non-synonymous mutations which can be missense mutations (which cause an amino acid substitution) or nonsense (which cause a premature stop codon).
