A Paradigmatic Case of Genetic Overlap Between Neurodevelopment Disorders and Schizophrenia Aligning with the Neurodevelopmental Continuum Hypothesis

Schizophrenia (SCZ) is a complex mental disorder, whose pathogenesis involves both environmental and genetic factors. Genetic risk is conferred through a combination of common variants and rare mutations, with point mutations and copy number variants (CNVs). Many of the genetic variants associated with SCZ have pleiotropic effects, influencing brain development and being shared with other neurodevelopmental disorders (NDDs), such as intellectual disability (ID). This overlap supports the concept of a neurodevelopmental continuum, suggesting shared genetic risk, at least between SCZ and ID, and most presumably among SCZ and many other NDDs. Here, we describe the case of a male patient whose clinical features align with this hypothesis. He presented cognitive and behavioral impairments preceding psychotic symptoms, further reinforcing the genetic and clinical interaction between SCZ and other NDDs. The patient's genetic profile was analyzed using array comparative genomic hybridization (a-CGH) and whole-exome sequencing (WES) to investigate the genetic determinants underlying his clinical condition. The genetic testing identified variants in loci associated with both SCZ and NDDs. Our findings highlight the need to integrate genetic assessments into psychiatrists' clinical practice. Moreover, this report contributes to the current body of evidence supporting the thesis on the neurodevelopmental continuum of SCZ.