Real-World Treatment of Schizophrenia in Adults With a 22q11.2 Microdeletion: Traitement dans le monde réel de la schizophrénie chez des adultes atteints du syndrome de microdélétion 22q11.2.

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One in every 4 individuals born with a 22q11.2 microdeletion will develop schizophrenia. Thirty years of clinical genetic testing capability have enabled detection of this major molecular susceptibility for psychotic illness. However, there is limited literature on the treatment of schizophrenia in individuals with a 22q11.2 microdeletion, particularly regarding the issue of treatment resistance. From a large, well-characterized adult cohort with a typical 22q11.2 microdeletion followed for up to 25 years at a specialty clinic, we studied all 107 adults (49 females, 45.8%) meeting the criteria for schizophrenia or schizoaffective disorder. We performed a comprehensive review of lifetime (1,801 patient-years) psychiatric records to determine treatments used and the prevalence of treatment-resistant schizophrenia (TRS). We used Clinical Global Impression-Improvement (CGI-I) scores to compare within-individual responses to clozapine and nonclozapine antipsychotics. For a subgroup with contemporary data (n = 88, 82.2%), we examined antipsychotics and dosage at the last follow-up. Lifetime treatments involved on average 4 different antipsychotic medications per individual. Sixty-three (58.9%) individuals met the study criteria for TRS, a significantly greater proportion than for a community-based comparison (42.9%; χ2 = 10.38, df = 1, p < 0.01). The non-TRS group was enriched for individuals with genetic diagnosis before schizophrenia diagnosis. Within-person treatment response in TRS was significantly better for clozapine than for nonclozapine antipsychotics (p < 0.0001). At the last follow-up, clozapine was the most common antipsychotic prescribed, followed by olanzapine, risperidone, and paliperidone. Total antipsychotic chlorpromazine equivalent dosages were in typical clinical ranges (median: 450 mg; interquartile range: 300, 750 mg). The results for this large sample indicate that patients with 22q11.2 microdeletion have an increased propensity to treatment resistance. The findings provide evidence about how genetic diagnosis can inform clinical psychiatric management and could help reduce treatment delays. Further research is needed to shed light on the pathophysiology of antipsychotic response and on strategies to optimize outcomes.