An autosomal recessive disorder characterized by global developmental delay, severe-to-profound intellectual disability, muscular hypotonia, seizures, brain anomalies, including thin corpus callosum and cerebellar atrophy, scoliosis, and mild facial dysmorphism. The disease is glycosylphosphatidylinositol biosynthesis defect 21 (Experimental Factor Ontology entry EFO_0010564). Also known as: neurodevelopmental disorder with brain anomalies, seizures, and scoliosis.