A loxP site flanked neomycin resistance gene cassette was inserted into intron 8 and exon 9 was replaced with a version with an engineered C1165T point mutation. The point mutation gives rise to the mouse equivalent of the Dravet syndrome-associated human Q390X nonsense mutation (Q389X in mouse) in the encoded peptide. The neo cassette was removed through cre-mediated recombination. (J:224480)