Partially complementary off-target messenger RNA (Off-target mRNA)

Partially complementary off-target messenger RNAs (mRNAs) are transcripts that are unintentionally regulated or degraded by RNA-targeted therapeutics, such as small interfering RNAs (siRNAs) or antisense oligonucleotides (ASOs) [1]. This phenomenon occurs when a therapeutic oligonucleotide binds to a non-target mRNA sequence that possesses partial complementarity, particularly within the 6-8 nucleotide "seed region" of an siRNA or through non-specific hybridization of an ASO [2][3]. Such interactions can lead to unintended gene knockdown via the RNA-induced silencing complex (RISC) or RNase H-mediated cleavage, potentially resulting in cellular toxicity or adverse clinical effects [4]. These off-target effects represent a significant safety challenge in the development of nucleic acid-based drugs, necessitating rigorous bioinformatic screening and chemical modifications to enhance specificity [5]. Monitoring these interactions typically involves comprehensive transcriptomic profiling to identify and mitigate risks associated with non-specific gene modulation [6]. Furthermore, chemical modifications like 2'-O-methyl or phosphorothioate linkages are often employed to reduce the affinity for off-target sequences while maintaining potency for the intended target [5]. Understanding the landscape of off-target binding is essential for establishing a safe therapeutic index for oligonucleotide medicines [3].

Other names

Off-target transcriptUnintended mRNA targetSeed-sequence off-targetNon-specific mRNA binding

Unintended sequence-specific hybridization leading to mRNA degradation via RISC or RNase H, or translational repression.