The other, well-established chromosomal abnormality associated with mental disorders is the deletion at 22q11. Patients with 22q11 deletion syndrome show schizophreniaor bipolar disorder-like mental symptoms (Paylor and Lindsay, 2006). The Df1 mice carrying the deletion at a relevant chromosomal region showed defects in sensorimotor gating, suggesting a schizophrenia-like behavioral abnormality (Paylor and Lindsay, 2006). These mice have not yet been analyzed as a ‘‘bipolar disorder model.’’ Further analysis of this model would be an interesting direction.