A form of congenital disorders of N-linked glycosylation characterized by severe neurological involvement, including hypotonia, developmental delay, intellectual disability, postnatal microcephaly, and progressive brain and cerebellar atrophy. Epilepsy with hypsarrythmia is frequently reported. Additional features that may be observed include failure to thrive, arthrogryposis multiplex congenita (AMC), vision impairment (optic atrophy, iris coloboma) and facial dysmorphism (hypertelorism with a broad nasal bridge, large and thick ears, thin lips, micrognathia). The disease is caused by loss of function mutations of the gene ALG3 (3q27.3). The disease is MONDO_0010998 (ALG3-congenital disorder of glycosylation). Also known as: ALG3-CDG, CDG syndrome type Id, CDG-Id, CDG1D, CDGId, carbohydrate deficient glycoprotein syndrome type Id, congenital disorder of glycosylation type 1d, congenital disorder of glycosylation type Id.