title: The novel transferrin E592A variant impairs the diagnostics of congenital disorders of glycosylation.
abstract: BACKGROUND
  The analysis of serum transferrin either by high-performance liquid chromatography (HPLC) or isoelectric focusing (IEF) is the standard diagnostic procedure in patients with the suspicion of a congenital disorder of glycosylation (CDG). Carbohydrate-deficient transferrin (CDT) is also analysed in monitoring programmes in cases of alcohol abuse. We report a novel transferrin variant that impairs the analysis using conventional methods and propose alternative forms of analysis.
  
  
  METHODS
  Transferrin samples were analysed using HPLC, immunoprecipitation followed by SDS-PAGE and IEF. Neuraminidase treatment followed by conventional IEF and electrospray ionization time of flight mass spectrometry (ESI-TOF MS) were applied before sequencing of the transferrin gene was performed.
  
  
  RESULTS
  The novel transferrin variant E592A, found both in homozygous and heterozygous form, causes an altered charge of the transferrin molecule, which changes the results of IEF and HPLC and mimics an increase in trisialo-transferrin. The change in charge can be detected either by neuraminidase digestion followed by IEF or by ESI-TOF MS.
  
  
  CONCLUSIONS
  Conventional diagnostic methods for CDG are hindered by the novel transferrin E592A. Neuraminidase treatment followed by IEF and ESI-TOF MS can identify the mutation. The mutation appears to be functionally normal.
authors.affiliation: Universitätsklinikum Münster, Klinik und Poliklinik für Kinder- und Jugendmedizin - Allgemeine Pädiatrie, Münster, Germany.
authors.forename: Julien H
authors.initials: JH
authors.lastname: Park
authors.affiliation: Universitätsklinikum Münster, Klinik und Poliklinik für Kinder- und Jugendmedizin - Allgemeine Pädiatrie, Münster, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Zühlsdorf
authors.affiliation: Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka University, Osaka, Japan.
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Wada
authors.affiliation: Vestische Kinder- und Jugendklinik, Universität Witten/Herdecke, Datteln, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Roll
authors.affiliation: Leibniz-Institut für Arterioskleroseforschung, Münster, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Rust
authors.affiliation: Universitätsklinikum Münster, Klinik und Poliklinik für Kinder- und Jugendmedizin - Allgemeine Pädiatrie, Münster, Germany.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Du Chesne
authors.affiliation: Universitätsklinikum Münster, Klinik und Poliklinik für Kinder- und Jugendmedizin - Allgemeine Pädiatrie, Münster, Germany.
authors.forename: Marianne
authors.initials: M
authors.lastname: Grüneberg
authors.affiliation: Universitätsklinikum Münster, Klinik und Poliklinik für Kinder- und Jugendmedizin - Allgemeine Pädiatrie, Münster, Germany.
authors.forename: Janine
authors.initials: J
authors.lastname: Reunert
authors.affiliation: Universitätsklinikum Münster, Klinik und Poliklinik für Kinder- und Jugendmedizin - Allgemeine Pädiatrie, Münster, Germany. Electronic address: marquat@uni-muenster.de.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Marquardt
mesh_terms: D016477:Artifacts; D001774:Blood Chemical Analysis / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D018981:Congenital Disorders of Glycosylation / Q000097:blood / Q000175:diagnosis* / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D006801:Humans; D047468:Immunoprecipitation; D007525:Isoelectric Focusing; D008297:Male; D009154:Mutation; D015203:Reproducibility of Results; D014168:Transferrin / Q000235:genetics*
chemical_list: D014168:Transferrin
keywords: Carbohydrate deficient transferrin; Congenital disorders of glycosylation; High-performance liquid chromatography; Isoelectric focusing; Mass spectrometry; Variant