CRISPR/Cas9 technology was used to flank exons 3 and 4 with loxP sites and inserted an FRT-flanked neomycin selection cassette downstream of exon 4 but upstream of the second loxP site. Cre-mediated recombination removed exons 3 and 4 and the neo cassette resulting in a frame-shift. Western blotting confirmed absence of protein in central nervous system tissue and sciatic nerve. (J:295996)