What types of errors dominate in DNA synthesis and sequencing for data storage?

• A. Substitutions, insertions, and deletions during synthesis; sequencing mistakes and read errors during retrieval.
• B. Substitutions only during synthesis and sequencing.
• C. Random environmental damage that does not involve insertions/deletions.
• D. Copy number variations during replication.

Answer: (A)

DNA data storage relies on writing data into DNA sequences and then reading it back with sequencing, so the most important error patterns come from those two steps. During synthesis, mistakes happen when the wrong base is incorporated, or when extra bases are added or some bases are skipped, giving substitutions as well as insertions and deletions. When you retrieve the data, sequencing itself can misread bases and occasionally introduce miscalls or indels, causing sequencing mistakes and read errors. This combination—substitutions, insertions, and deletions arising in synthesis, plus sequencing mistakes and read errors during retrieval—defines the dominant error landscape you must design against with error-correcting schemes. Environmental damage can occur, but in typical storage and sequencing workflows it’s not the main pattern, and copy-number variations are phenomena from cellular replication, not the DNA storage pipeline.