There is also compelling genome-wide evidence that the large numbers of identified but as yet unstudied intronic, intergenic, and antisense ncRNAs have intrinsic indices of functionality (Table 2), as indicated by the following: (i) the conservation of their promoters, splice junctions, exons, predicted structures, genomic position, and expression patterns [2], [26]–[36]; (ii) their dynamic expression and alternative splicing during differentiation [13],[31],[32]; (iii) their altered expression or splicing patterns in cancer and other diseases [37]–[49]; (iv) their association with particular chromatin signatures that are indicative of actively transcribed genes [31],[32]; (v) their regulation by key morphogens and transcription factors [31],[32],[49],[50]; and (vi) their tissue- and cell-specific expression patterns and subcellular localization [16], [17], [19]–[22], [49], [51]–[56].
