What would happen if rna polymerase initiated transcription 1 base upstream of its normal starting point?

there would be a frame shift mutation. so the frame would be off, because during translation the rna is changed to protein by reading every 3 codons for a amino acid so if the sequence is supposed to be ACT TAG TTA GAT, it would now read XAC TTA GTT ATA TXX. this usually is a major problem because every downstream codon is mutated or changed so it usually would just make nonsence and not make a protein but if it somehow did make a functional protien then it coudl also be a problem because if the protien it made is oncogenic or something that would be bad.