CDG (congenital disorders of glycosylation). Differential hereditary ataxia in adulthood diagnosis

Congenital disorders of glycosylation (CDG) are a group of hereditary multisystem diseases due to different defects of enzymes or transport molecules involved in the synthesis of glycoproteins. CDG-la is the most common subtype, with cerebellar ataxia as the main neurological symptom. Currently there is little information about CDG-la manifestation in adulthood. Here we present two sisters in whom the diagnosis of CDG-la was made in the fourth decade of life and who to our knowledge are the oldest known patients with the disorder in Germany. The clinical course of the disease was typical, although less severe than previously described. The carbohydrate-deficient transferrin (CDT) level was increased but lower than in other CDG patients. Isoelectric focusing of transferrin revealed changes typical of CDG, whereas those of alpha 1-antitrypsin were only moderately pathologic. This might be due to the milder manifestation of the disease in our patients or it could be indicative of a stabilization of the disease after puberty. The CDG should be included in the differential diagnostic workup of hereditary cerebellar ataxia in adults.