Bestudering van transferrienglikosilering as 'n merker vir glikosileringsdefekte

Abstract

The CDG-syndromes, usually characterised by psychomotor retardation, is a newly described group of diseases and no case has yet been described in South Africa. The purpose of this study was the development of a standard method for studying of the glycosylation of transferrin as a marker for glycosylation defects and the application of the method to South African patients. Transferrin shows a degree of microheterogeneity due to differences in carbohydrate composition of the N-glycans bound to the peptide and is therefore very useful in the study of glycosylation defects. !so-electric focusing (IEF) is often used in the study of transferrin glycosylation. An IEF-technique was developed to study transferrin patterns; transferrin of a number of different control persons was studied and the known transferrin pattern in normal people (high levels of tetrasialotransferrin, with lower levels of tri-, di- and pentasialotransferrin, respectively) was observed in these controls. To validate this standardised IEF-technique for this study, transferrin from a number of different alcoholics was analysed and the characteristic abnormal transferrin pattern with raised levels of disialotransferrin and also asialotransferrin, was observed in these patients. The transferrin of seventeen possible CDG-cases was analysed and in four of these, abnormal patterns were observed. Patient ES showed a pattern corresponding to patterns of positive controls of CDG type 1, while another patient (patient ST) showed transferrin patterns corresponding to known patterns for CDG type 3. A patient (patient SN) whose transferrin pattern corresponds to known patterns for CDG type 2, was also identified and in another case (patient DL), a previously unknown but unmistakeably abnormal transferrin pattern was observed. Unfortunately, clinical histories of all of these cases are not at all complete and further studies (including enzyme analyses) will have to be performed to verify these results.