the Phenotypic and Genetic Profile of Patients With Early Onset Schizophrenia Associated With Autism Spectrum Disorder.

Introduction: Early-onset Schizophrenia (EOS) is a rare and severe condition displaying early dissociative disorder (i.e., age of onset \< 18 years). A higher rate of neurodevelopmental abnormalities is observed in EOS compared to adult onset schizophrenia (AOS). Thus, patients affected by EOS typically present intellectual, learning, communication or neuromotor impairments, as well as attention deficit hyperactivity disorder. Early signs of autism spectrum disorders (ASD) are also found in 30% of patients with EOS. Cytogenetics abnormalities, including copy number variations (CNVs), are frequent in neurodevelopmental disorders and have been linked to ASD physiopathology. Implicated genes encode proteins playing a role in brain development, synaptic morphology, plasticity and neurogenesis. In addition, an increasing number of genetic abnormalities are shared by EOS and ASD, suggesting that schizophrenia can be considered a neurodevelopmental disorder. The main objective of the present study is to identify mutations in genes involved in neurodevelopmental pathways in our cohort of patients affected by both EOS and ASD. Method and analysis: We describe here a multicenter study in a pediatric population named "Exploration and characterization of genetic and phenotypic profile of the 'early dissociative disorder' associated with autism spectrum disorder (GenAuDiss)". The study started in April 2014. The inclusion criteria are: age 7 to 22 years, diagnoses of EOS with co-morbid ASD and IQ \> 50; as well as parents and siblings of the included patients. We perform standardized psychiatric assessments (MINI, K-SADS-PL, PANSS, SANS, TCI 226, and AQ) and neurocognitive evaluations (IQ, TMT A/B, and verbal fluency). Then, we study variants of the coding part of the DNA (exome), using next generation sequencing (NGS) process on trio (mother, father, and child). Divers bio-informatics tools such as RVIS and PolyPhen-2 will be used to prioritize the potential candidate genes. The inclusion period of this study will end in November 2019. Ethics and dissemination: The study protocol was approved by the Ethics Committee 'Sud Méditerrané V' (number 14.002) and by the French National Agency for Medicines and Health Products Safety (ANSM 2013-A01699-36). All patients, their parents and siblings signed informed consent upon enrolment in the study. Results of the present study should help to unravel the molecular pathology of EOS, paving the way for an early therapeutic intervention