One of the most intriguing developments in modern molecular biology is the discovery that a large proportion of the eukaryotic genome gives rise to RNA molecules that do not encode proteins. The sheer scale of this phenomenon has forced scientists to realise that the complexity of genetic programming in higher organisms including humans has been greatly underestimated. To the surprise of many, most recent studies indicate that these so-called non-coding RNAs (ncRNAs) appear to be engaged in a variety of important biological functions through the regulation of gene expression. At the heart of our research is a distinct class of ncRNAs known as natural antisense transcripts or NATs.