Fig. 1.

Classification of by their genomic location relative to nearby protein-coding genes. (i) Intergenic lncRNAs: lncRNAs located between protein-coding genes; (ii)Antisense lncRNAs: lncRNAs transcribed in the opposite direction of nearby protein-coding genes, and span over at least one exon; (iii)Intronic lncRNAs: lncRNAs that originate from intronic regions of protein-coding genes; (iv) Bidirectional lncRNAs: lncRNAs that initiate transcription in a divergent fashion from the promoter of nearby protein-coding gene.