Journal of Advances in Biology & Biotechnology

Natural antisense transcripts (NATs) are RNA molecules transcribed from the DNA strand opposite a protein-coding or non-coding gene, and they constitute one of the most pervasive yet mechanistically heterogeneous classes of the mammalian non-coding transcriptome. Since large-scale transcriptomic surveys demonstrated that a majority of transcriptional units in the human and mouse genomes are subject to antisense transcription, NATs have been implicated in transcriptional interference, chromatin remodelling through RNA:DNA triplex formation, microRNA sponging, modulation of mRNA stability, and direct control of translation initiation. This review critically synthesises the molecular evidence linking NATs to neurodegenerative, oncological and cardiovascular disease, with particular attention to BACE1-AS in Alzheimer's disease, HOTAIR in epithelial malignancies, and CDKN2B-AS1 (ANRIL) in atherosclerosis. Rather than treating this literature as a uniformly supportive body of evidence, the review foregrounds points of genuine scientific contention, including the divergence between cell-culture knockdown data and in vivo knockout phenotypes for HOTAIR, and the persistent difficulty of distinguishing cis-acting transcriptional interference from trans-acting RNA-mediated regulation. The therapeutic section evaluates antisense oligonucleotide strategies (AntagoNATs) and SINEUP-based translational enhancers as emerging modalities capable of achieving locus-specific, reversible upregulation of haploinsufficient genes, contrasting this mechanism with the predominantly inhibitory pharmacology of conventional oligonucleotide therapeutics. Methodological weaknesses recurring across the primary literature are assessed, including reliance on transformed cell lines, inconsistent knockdown efficiencies, sparse replication across independent laboratories, and limited attention to species-specific conservation of NAT sequences. The review concludes that while the mechanistic diversity of NAT-mediated regulation is now well established at the level of individual case studies, the field lacks generalisable rules predicting when a given antisense transcript will act in cis versus trans, and clinical translation remains constrained by delivery, tissue specificity and long-term safety considerations. Priorities for future research are identified, including standardised functional validation pipelines, comparative genomic conservation analyses, and controlled clinical evaluation of AntagoNAT and SINEUP platforms beyond monogenic haploinsufficiency disorders.