The gene was disrupted by insertion of a PGK-neo cassette into exon 2 just downstream of the translation initiation codon via homologous recombination. Northern blot analysis of brain RNA from mutant animals detected a 0.9 kb mutant transcript containing the PGK-neo insertion. Western blot analysis of several tissues from newborn homozygous mutant animals showed an absence of protein product. (J:44181)