A novel C2 transferrin variant interfering with the analysis of carbohydrate-deficient transferrin

Background Carbohydrate-deficient transferrin (CDT) is used as a marker for chronic alcohol abuse. The presence of genetic transferrin variants might affect an individual's iron status and can interfere with CDT analysis. We report on the identification of a patient carrying a novel transferrin variant. We describe the performance of the various CDT methods in its detection and the associated iron status. Methods DNA of the coding region of transferrin was sequenced and CDT levels were analysed using four different methods: high pressure liquid chromatography (HPLC), capillary zone electrophoresis (CZE), immunochemistry and iso-electric focussing (IEF). Results A novel transferrin variant, T139M, was found as a heterozygous genotype in the index patient and all of his four living direct family members (c.416 C > p.Thr139Met). CDT analysis of the variant by HPLC and CZE was compromised as a result of the coelution of the different isoforms. CDT levels could be quantified by immunochemistry. Similar results were obtained using IEF analysis. The presence of the C2 transferrin variant did not affect iron status in any of the investigated patients. Conclusions Transferrin T139M, present as a heterozygous genotype, interferes with CDT analysis by HPLC and CZE but not by immunochemistry. Physiologically, it appears to be functionally normal.