A form of congenital disorders of N-linked glycosylation characterized by feeding problems, mild-to-moderate neurologic involvement with hypotonia, poor head control, developmental delay, ataxia, strabismus, and seizures, ranging from febrile convulsions to epilepsy. Retinal degeneration has also been reported. A minority of patients show other manifestations, particularly intestinal (such as protein-losing enteropathy) and liver involvement. The disease is caused by loss of function mutations of the gene ALG6 (1p31.3). The disease is Monarch Disease Ontology term MONDO_0011291 (ALG6-congenital disorder of glycosylation 1C). Also known as: ALG6 congenital disorder of glycosylation, ALG6-CDG (CDG-Ic), ALG6-CDG1C, CDG syndrome type Ic, CDG-Ic, CDG1C, CDGIc, carbohydrate deficient glycoprotein syndrome type Ic.