Increased Carbohydrate-deficient Transferrin Concentration and Abnormal Protein Glycosylation of Unknown Etiology in a Patient with Achondroplasia

Abstract

We report the observation of abnormal protein glycosylation in a patient with achondroplasia in whom known causes of impaired glycosylation could not be found. Automated isoelectric focusing (IEF) was performed in our laboratory for the investigation of glycosylation disturbances of transferrin (1)(2). All procedures were carried out in accordance with the Helsinki Declaration of 1975 as revised in 1996. We used surplus serum samples as controls, and surprisingly, in one of those, IEF revealed a moderate increase in disialotransferrin and a slight increase in asialotransferrin (Fig. 1⇓ , lane 1) compared with control serum (Fig. 1⇓ , lane 2). A similar IEF pattern has been described, e.g., in alcohol abuse (3) or in carbohydrate-deficient glycoprotein (CDG) syndrome (4). The patient’s isotransferrin pattern had been stable in different blood samples for more than 3 years. The hypoglycosylation of transferrin was confirmed by an increased carbohydrate-deficient transferrin (CDT) concentration of 44 units/L (upper reference limit, 20 units/L) determined by the CDTect assay (Pharmacia & Upjohn). Figure 1. Fe2-isotransferrin ( Fe 2 -Tf ) band patterns in serum and cerebrospinal fluid ( CSF ) obtained by automated IEF. CSF serves as reference for the localization of isotransferrin bands. Lane 1 , patient’s serum; lane 2 , control serum. Clinically, the patient was a 41-year-old man in good general health. His past history included well-controlled arterial …