A de novo truncating variant in CSDE1 in an adult-onset neuropsychiatric phenotype without intellectual disability.

Variants in CSDE1, a gene encoding a constrained RNA-binding protein, have recently been associated with a spectrum of neurodevelopmental conditions encompassing autism, seizures and ocular abnormalities. According to previously reported individuals, pathogenic variants in CSDE1 are typically associated with developmental delay and intellectual disability. Here, we report one individual with normal neurodevelopment and adult-onset neuropsychiatric features (i.e., acute psychosis) due to the novel de novo truncating variant c.2272C>T, p.(Gln758*) in CSDE1 (NM_001242891.1). Neuropsychological assessment confirmed deficits regarding verbal fluency, semantic memory, executive function and processing speed. Overall, our findings expand the phenotypic spectrum of CSDE1-related disorder towards the mild end.