Low dose clozapine controls adult-onset psychosis associated with the neurogenic ataxia-retinitis pigmentosa (NARP) mutation

Little is known regarding the management of psychotic disorders in NARP syndrome. We report the case of a 30 year-old Caucasian male, born from healthy unrelated parents. During his first year, he presented cerebellar ataxia with pyramidal syndrome. Sequencing his leukocyte and urinary mtDNA detected a heteroplasmicmutation (95%) in the MTATP6 gene (m.8993TNC) [1]. At 28 years, he presented a psychotic episode with psychomotor agitation and delusional persecutory beliefs without cognitive decline. Brain MRI showed a cerebellar atrophy and bilateral striatal hyper-intensities (Fig. 1A). Antipsychotics lead to dystonia, akathisia and extrapyramidal syndrome with falls. The patient remained aggressive with faecal and urinary incontinence. Thus, a switch to clozapine was suggested [2]. Clozapine was administrated at low dose (12.5 mg/day, reaching 37.5 mg/day in four weeks). The patient experienced a complete