Congenital disorder of glycosilation PMM2-CDG

Congenital glycosylation disorders represent a group of genetically determined diseases which violate the synthesis and addition of glycans to glycoproteins and glycolipids, and also the synthesis of glycosylphosphatidyl inositol. The most common defects are the defects of protein N-glycosylation. Jaken syndrome, a congenital disorder of PMM2-CDG glycosylation, is the most commonly diagnosed type (about 800 cases worldwide). However, there are only a few descriptions of clinical cases in the Russian literature. The article presents a clinical observation of a child with this type of congenital glycosylation disorder due to a defect in phosphomannomtase 2 (PMM2 gene). The diagnose was based on the combination of clinical, laboratory and instrumental data: a characteristic phenotype, hyperinsulinism, delayed physical and psychomotor development, neurological manifestations, coagulopathy, liver damage, exudative enteropathy, abnormal forms of transferrin, PMM2 gene mutations associated with Jaken’s syndrome. For the first time the authors described positive clinical and laboratory dynamics due to the inclusion of D-mannose to the therapy for this type of congenital glycosylation disorder.