Congenital disorder of glycosylation type Ia revealed by hypertransaminasemia and failure to thrive in a young boy with normal neurodevelopment.

Congenital disorders of glycosylation (CDG), formerly called carbohydrate deficient glycoprotein syndromes, are a group of inherited metabolic errors resulting in defective synthesis or processing of N-glycoproteins or, in some cases, of O-glycans. Hypoglycosylation of proteins leads to variable, generally severe, problems in affected individuals. Since CDG was first described in 1980 (1) several subtypes have been identified. Following recent recommendations (2), congenital disorders of N-glycosylation are divided into two groups. CDG type I comprises defects in the assembly of N-glycans in cytosol and endoplasmic reticulum, and CDG type II refers to defects in the processing of the protein-bound glycans in the endoplasmic reticulum or in the Golgi compartment. The most frequent subtype is CDG Ia, which originates from a phosphomannomutase 2 deficiency caused by a mutation of the PMM gene locus on chromosome 16p13 (3,4). We report the case of a 6-year-old boy who presented at 2 years of age with abnormal serum transaminases and failure to thrive as the main signs of a type Ia CDG syndrome. Neurologic signs were detected only on careful examination of the patient, as he showed only slight motor clumsiness and his neurodevelopment quotient (Brunet-Lézine) was normal.

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