Complexities of mammalian transcriptome revealed by targeted RNA enrichment techniques

Studies using highly sensitive targeted RNA enrichment methods have shown that a large portion of the human transcriptome remains to be discovered and that most of the genome is transcribed in a complex, interleaved fashion charac-terized by a complex web of transcripts emanating from protein coding and non-coding loci. These results resonate with those from single-cell transcriptome profiling endeavors that reveal the existence of multiple novel, cell type-specific transcripts and clearly demonstrate that our understanding of the complexities of the human transcriptome is far from being complete. Here, we review the cur-rent status of the targeted RNA enrichment techniques, their application to the discovery of novel cell type-specific transcripts, and their impact on our under-standing of the human genome and transcriptome.