Figure 1: Classification of long noncoding RNAs. Long noncoding RNAs (lncRNAs) are categorized as exonic, intronic, intergenic, antisense, or overlapping based on their genomic location relative to a protein-coding gene. Exonic lncRNAs share exons with a protein-coding gene. Intronic lncRNAs are transcribed within the introns of a protein-coding gene. Intergenic lncRNAs are transcribed within the regions between two protein-coding genes. Antisense lncRNAs are located on the opposite strand from a protein-coding gene. Overlapping lncRNAs are transcripts that contain a protein-coding gene within its intron.