Strandagnostic

Strand-agnostic, also referred to as unstranded, is a term used in molecular biology and sequencing to describe methods, data, or analyses that do not preserve or rely on information about which DNA or RNA strand a read originated from. In the context of RNA sequencing, strand-agnostic libraries are prepared without maintaining strand orientation, so reads mapped to the genome cannot be confidently assigned to sense or antisense transcripts. This contrasts with strand-specific (stranded) protocols that retain strand information and enable more precise attribution of reads to overlapping genes.

In practice, strand-agnostic sequencing often arises from certain library preparation methods, such as total RNA sequencing or some older ribosomal RNA-depleted protocols. It is common in historical datasets or experiments where strand information is not essential for the research aim. When analyzing strand-agnostic data, quantification pipelines treat reads as strand-insensitive; many tools offer a non-stranded mode for counting reads to gene models.

The main implications of strand-agnostic data relate to resolution and interpretation. Without strand information, reads that overlap genes on opposite strands or reside in regions with pervasive antisense transcription may be ambiguously assigned, potentially biasing expression estimates for overlapping loci. For studies requiring precise strand-specific expression profiles, researchers typically employ stranded library preparation and strand-aware quantification, which can improve accuracy and interpretability in complex transcriptomes.