The statement that a mutation that replaces a single nucleotide in a protein‑coding region of DNA will replace amino acid with any other amino acid is incorrect.
We know about genetic code's redundancy meaning more than one codon codes for the same amino acid therefore a single nucleotide change may not necessarily change the amino acid. This type of mutation is known as synonymous mutation. These mutations occur when the DNA sequence that codes for the amino acids in a protein sequence are altered without altering the amino acid that is encoded. These modifications typically take place in the third position of a codon because of the genetic code's redundancy.
