NFU1 and Neurodevelopmental delay: Here, we report 19 affected individuals from 10 independent families with ultra‐rare bi‐allelic NFU1 missense variants associated with a phenotype ranging from early‐onset pure to complex hereditary spastic paraplegia (HSP) characterized by a longer survival (16/19) and neurodevelopmental delay (NDD) with severe hypotonia (3/19).