The effects of the variants on U2AF2 –RNA interactions are unlikely to be sequence-specific, since Arg146interacts similarly with either uridine or cytidine.13 Accordingly, U2AF2 Arg146 itself is marked by a de novo, NDD-associated mutation, Arg146Gly,4 which likewise is expected to disrupt RNA interactions. This evidence concerns the gene U2AF2 and Neurodevelopmental delay.