In PLoS Genetics this week, Patrick Schorderet and Denis Duboule at Switzerland's Federal Institute of Technology discuss the "structural and functional differences in the long, non-coding RNA Hotair in mouse and human." In particular, Schorderet and Duboule say that "the cognate mouse Hotair is poorly conserved in sequence" and add that "its absence, along with the deletion of the HoxC cluster, has surprisingly little effect in vivo, neither on the expression patt