What would happen if you added an extra cytosine to your dna?

The answer is; A Frameshift mutation would occur downstream from the point the cytosine is added

Frameshift mutation means that the 3-base sequence on the DNA, known as codons, will change due to the addition – shifting it by a single nucleotide. The consequences of this are that the proteins that will be translated from the genes will be different and this will cause a threat to your health.

i would think it's dendrites