The targeting construct is designed to delete 4 base pairs (TCTT) in exon 12 of the gene. This deletion is analogous to a deletion found in patients with neuropsychiatric disorders such as schizophrenia. A loxP flanked neomycin (neo) resistance cassette was inserted downstream of the deletion. Germ line, cre mediated recombination removed the neo cassette. (J:304928)