A cassette containing a reverse orientation (relative to Nespas) polyadenylation sequence and a self-excising neo cassette was inserted into exon 1. Cre-mediated recombination removed the neo cassette. The 94% reduction in Nespas transcript expression was confirmed by RT-qPCR on newborn brain extracts with paternal inheritance of the allele. RT-qPCR on newborn brain extracts confirmed reduced Nesp (Gnas) expression when the allele is inherited marternally but increased expression when the allele is paternally inherited. (J:171195)