Neurodevelopmental disorders (NDDs) show a wide range of overlapping clinical features. Intellectual disability (ID), developmental delay (DD), autism spectrum disorder (ASD), attention-deficit hyperactivity disorder (ADHD), language and communication disorders with or without motor abnormalities and/or epilepsy have been reported associated to single or multiple genes but in many cases the genetic basis remains unknown. The increasingly use of array-CGH has significantly improved the yield of diagnosing genomic disorders and led to the identification of several novel microdeletion and microduplication syndromes. TANC2 encodes a synaptic scaffold protein interacting with multiple neuropsychiatric disorder-related postsynaptic density (PSD) proteins in dendrites. Here, we describe a new case of TANC2 gene disruption in a 17q23.3 de novo microdeletion identified by array-CGH. The patient presented craniofacial dysmorphic features, hypotonia, and severe cognitive and motor impairment. In conclusion, our data add a further line of evidence supporting the role of TANC2 in NDDs and will help further researches to elucidate the regulatory mechanism of synaptic function and plasticity related to TANC2 haploinsufficiency.