Base substitution mutations can have the following molecular consequence, EXCEPT:
Reading frame changes downstream to the mutation site occurs in frameshift mutations but not in base substitution mutations. Ref: Harper Illustrated Biochemistry, 26th Edition, Chapter 38, Pages 361-64
Changes one codon for an amino acid into another codon for that same amino acid
Codon for one amino acid is changed into a codon of another amino acid
Reading frame changes downstream to the mutation site
Codon for one amino acid is changed into a translation termination codon