Fig. 1. Patients with 22q11.2 deletion syndrome (22q11.2DS) schizophrenia are maintained on a significantly lower therapeutic dose of clozapine than patients with idiopathic schizophrenia (P = 0.002).
The two 22q11.2DS-schizophrenia patients with doses ≤150 mg had been maintained in this range for at least 1 year; one was receiving adjunct antipsychotic flupentixol (4.5 mg) treatment. Of the three patients in the idiopathic group on a clozapine dose ≤150 mg, one was maintained on this dose for 4 years; the other two discontinued within 9 and 28 weeks, respectively (the latter on adjunct antipsychotic perphenazine (48 mg) treatment) and were not titrated above this low dose range.