Answer:
The impact of the codon changing to A has a missense mutation on the protein. The original amino acid was Histidine and mutated into Leucine.
Step-by-step explanation:
*If you do not know how to use a codon chart you can ask me, just comment it.*
ok, let's first see what a missense mutation actually is.
missense mutation - A changed DNA sequence that changes a amino acid completely from the original amino acid.
The original strand you have to convert it, CTC is CAC that is how it originally is Histidine, the mutated DNA strand is CAC, but converted is CUC which is Leucine.
Hope that helped, if not, I can go in depth. :)