Determination of genetic transferrin variants in human serum by high‐resolution capillary zone electrophoresis^†

Abstract

High-resolution capillary zone electrophoresis in the routine arena with stringent quality assurance is employed for the determination of carbohydrate-deficient transferrin in human serum. The assay comprises mixing of human serum with a Fe(III) -containing solution prior to analysis of the iron-saturated mixture in a dynamically double-coated capillary using a commercial buffer at alkaline pH. In contrast to other assays, it provides sufficient resolution for proper recognition of genetic transferrin variants. Analysis of 7290 patient sera revealed 166 isoform patterns that could be assigned to genetic variants, namely, 109 BC, 53 CD, one BD and three CC variants. Several subtypes of transferrin D can be distinguished as they have large enough differences in pI values. Subtypes of transferrin C and B cannot be resolved. However, analysis of the detection time ratios of tetrasialo isoforms of transferrin BC and transferrin CD variants revealed multimodal frequency histograms, indicating the presence of subtypes of transferrin C, B and D. The data gathered over 11 years demonstrate the robustness of the high-resolution capillary zone electrophoresis assay. This is the first account of a capillary zone electrophoresis based carbohydrate-deficient transferrin assay with a broad overview on transferrin isoform patterns associated with genetic transferrin variants.

Monitoring of transferrin isoforms in biological samples by capillary electrophoresis

“…D and ), and one with a tiny shift, and thus the occurrence of double peaks (Tf‐CC variant, Fig. D) . Almost 200 isoform patterns could be assigned to genetic variants during 15 years of CDT analysis in our laboratory.…”

“…Subtype III (Fig. B) is the most prevalent, monitored in the sera of our patient samples . For a long time, only tiny differences in the Tf‐BC patterns were observed .…”

“…C) and several samples exhibited a Tf‐CC pattern (Fig. D, ). No samples were found that encompassed Tf‐BB or Tf‐DD variants.…”

“…Electropherograms showing four subtypes of Tf‐CD heterozygote patients (bottom graphs) together with those of ClinCheck serum control samples (upper graphs). The groups IV, III, II, and I are those described in . Key as for Fig.…”

Analysis of genetic variants of transferrin in human serum after desialylation by capillary zone electrophoresis and capillary isoelectric focusing

“…Tf‐B variants have lower p I values than Tf‐C and occur with lower frequencies, whereas genetic Tf‐D variants have higher p I values than Tf‐C and are reported to be rare in Caucasians, but not in some other populations. A systematic assessment of genetic variants of iron saturated Tf in human serum determined by high‐resolution CZE was recently reported from our laboratory . This work revealed that genetic variants are easily recognized when a high‐resolution separation method is employed.…”