Facts:

• Amplified ribosomal DNA restriction analysis (ARDRA) involves the amplification of the 16S rRNA gene (1500 bp) followed by enzymatic restriction and gel electrophoresis.
• The terminal transferase activity of Taq Polymerase promotes the 3' nontemplated addition of adenine ('plus A').
• The final extension step is done in order to give the DNA polymerase extra time to completely adenylate all double-stranded PCR product.

Question:

"After initial denaturation at 95°C for 5 min, the reaction mixture was run through 35 cycles of denaturation at 95°C for 45 s, annealing at 50°C for 45 s, and extension at 72°C for 1 min followed by a 7-min extension period at 72°C."

[Koeleman JG, Stoof J, Biesmans DJ, Savelkoul PH, Vandenbroucke-Grauls CM. Comparison of amplified ribosomal DNA restriction analysis, random amplified polymorphic DNA analysis, and amplified fragment length polymorphism fingerprinting for identification of Acinetobacter genomic species and typing of Acinetobacter baumannii. J Clin Microbiol. 1998 Sep;36(9):2522-9. doi: 10.1128/JCM.36.9.2522-2529.1998. PMID: 9705386; PMCID: PMC105156.]

How can a single base variation affect ARDRA?

This is a terminal base so it can't affect a restriction site sequence.

I also see that this can't affect the presence of a single band in the post-PCR verification step unless a gel with very high-resolution power is used.