A form of congenital disorders of N-linked glycosylation characterized by progressive microcephaly, hypotonia, developmental delay, drug-resistant infantile epilepsy, and hepatomegaly. Additional features that may be observed include failure to thrive, pericardial effusion, renal cysts, skeletal dysplasia, facial dysmorphism (frontal bossing, hypertelorism, depressed nasal bridge, low-seated ears, large mouth) and hydrops fetalis. The disease is caused by loss-of-function mutations in the gene ALG9 (11q23). The disease is MONDO_0012117 (ALG9-congenital disorder of glycosylation). Also known as: ALG9-CDG, CDG syndrome type IL, CDG-IL, CDG1L, carbohydrate deficient glycoprotein syndrome type 1L, congenital disorder of glycosylation type 1L, mannosyltransferase 7-9 deficiency.