While the function of the MN1 C-terminus remains unknown, mutations affecting this region are causative of a human congenital syndrome, “MN1 C-terminal truncation syndrome” (MCTT), manifested by neurodevelopmental disorders resulting in intellectual disability, brain abnormalities, and distinctive facial features (midface hypoplasia, cleft palate, and other skeletal anomalies) (24, 53, 54). This evidence concerns the gene MN1 and CEBALID syndrome.