SLC39A8 and Intellectual disability: LOF mutations in slc39a8 cause SLC39A8-congenital disorder of glycosylation (SLC39A8-CDG, or CDG type 2n), a congenital disorder of glycosylation associated with Mn deficiency.7–11 This multisystem infantile-onset syndrome is characterized by global developmental delay, intellectual disability, hypotonia, movement abnormalities (including dystonia), seizures and variable dysmorphic features.