Table 1.

Classification of long non-coding RNAs (lncRNAs) based on genomic location.

lncRNA	Genomic context	Examples
Intergenic lncRNAs	Transcribed inter genetically from both strands by RNA Pol II	Xist, H19, HOTAIR, MALAT1
Intronic lncRNAs	Originates from introns of protein coding genes	COLDAIR, PPP3CB, MAP3K14 and DAPK1 loci
Transcription start site-associated lncRNAs	Transcribed from promoter upstream region and enhancer region by RNA pol II	Associated with EXT1 and RBM39 genes, associated with RNAF12 and CCDC52 genes
Natural antisense transcripts	Transcribed from the opponent strand of either protein coding or non-protein coding genes	Xist/Tsix, Kcnq1/Kcnq1ot1, Igf2r/Air
Pseudogene lncRNAs	Residues of their parental genes that lost encoding function due to mutations	Xist evolved from protein-coding gene Lnx3