About a quarter of the human genome involves introns. An exciting recent finding of great significance is that a further quarter of the human genome is transcribed to RNA but not translated into protein (Mattick, 2004), and much of the genome is transcribed from both strands (Birney, Stamatoyannopoulos, Dutta, Guigo, Gingeras et al., 2007). This other RNA, which can be anywhere in the genome (not just near protein-coding genes), may also include ncRNA responsible for the regulation of protein-coding genes (Kapranov, Cheng, Dike, Nix, Duttagupta et al., 2007). This has led the way to a new world of regulatory networks across the genome and to many new targets for potential sources of genetic variation (Mattick, 2005; Mattick & Makunin, 2006). This finding suggests the need for a much broader view of the word gene.
