In conclusion, we report a novel neurodevelopmental disorder characterized by severe impairment of brain and cerebellar development and found its association with biallelic loss-of-function variants in NAV2. The neuroradiological phenotype of the affected individual is characterized by a complex brain malformation with a peculiar combination of cerebellar and brainstem malformations including vermian hypoplasia, extensive foliation defects, pontine hypo-dysplasia, and splayed thin superior cerebellar peduncles with a molar tooth-like configuration. This evidence concerns the gene NAV2 and neurodevelopmental disorder.