Which statement best describes the impact of GC content on sequencing and synthesis in DNA data storage?

• A. GC content has no impact on read accuracy.
• B. Balanced GC content always yields maximum data density.
• C. Very high or very low GC content can hinder synthesis/read accuracy; balanced GC improves stability and sequencing performance.
• D. GC content determines data encoding length.

Answer: (C)

GC content, the proportion of G and C bases in a DNA sequence, directly influences how stable the duplex is and how easily enzymes can synthesize and read it. GC pairs form three hydrogen bonds, so sequences with many GC bases are more thermally stable and can develop secondary structures. In DNA data storage workflows, those extreme stabilities or instabilities can cause synthesis dropouts, polymerase stalling, and biased or inaccurate sequencing reads. Keeping GC content balanced helps keep melting temperatures in a practical range and minimizes troublesome structures, leading to more reliable synthesis and better sequencing performance. This is why balanced GC content improves stability and sequencing performance. The other statements miss these practical impacts: GC content does affect read accuracy; data density isn’t dictated by GC balance, and encoding length is set by the data, not GC content.