Boot and colleagues' observation of clozapine efficacy should, however, be interpreted with caution considering the small number of cases. In our article, we presented case reports in a supplement with information on treatment and response (2). The Danish patient received numerous antipsychotics, including clozapine, and the condition was nonetheless considered treatment refractory. The German patient also received numerous antipsychotics, although not clozapine, and also showed little response to treatment. We have little information on the treatment and response for one of the British patients (female), while the psychotic symptoms in the other patient (male) did not respond well to antipsychotics (no mention of clozapine). The psychotic symptoms responded to antipsychotics during the early course of illness in our Icelandic patients, but the symptoms subsequently responded even better to clozapine in the patient diagnosed with schizophrenia, and the manic and psychotic symptoms responded to lithium and antipsychotics in the patient diagnosed with bipolar I disorder.