Jos Jansen

5 123 Screening for abnormal glycosylation in a cohort of adult liver disease patients show that fucosylation of transferrin is elevated in samples from LTx candidates compared to CLD patients and healthy controls. Hyperfucosylation of transferrin was shown to be the cause of chromatographic abnormalities in CDT testing, or so-called “di-tri-bridging” (i.e. poor resolution of disialoTF from trisialoTF).(32) Di-tri-bridging is associated with liver disease and is more frequent in cirrhosis than in non-cirrhotics.(33) Somewhat older data exists on fucosylation of haptoglobin in liver disease and shows hyperfucosylation in patients with alcoholic liver disease and primary biliary cholangitis.(34) A more recent paper showed increased hyperfucosylated glycans on haptoglobin in HCC as well as in cirrhosis. (35) Previous work on serum glycan analysis in liver cirrhosis identified increased hypogalactosylation and increased modification of the serum N-glycome with a bisecting N-acetylglucosamine.(9) Log ratios of different glycans could with good sensitivity and specificity discriminate between early fibrosis and cirrhosis. A follow-up study showed that undergalactosylation was due to the IgG-derived glycan fraction.(36) This is in line with our data that did not show undergalactosylation in any sample. Also, no glycans were observed within our cohort with a bisecting N-acetylglucosamine. This might be explained by protein specific glycosylation. Strengths and limitations One strength of our study was that we included a wide range of liver disease patients for analysis. We took care to include patients with mild liver disease but also those with advanced chronic liver disease in need for LTx. Our efforts led to the establishment of a large sample size of over 1000 liver disease patients which adds to the robustness of the study. Additionally, we were able to screen these samples with high resolution mass spectrometry that provided in depth analysis of the intact transferrin glycoprotein, including fucosylation, loss of galactose and the absence of complete glycans. A limitation of our study is because of its retrospective character. We had access to collected serum samples but were not in possession of fresh plasma or fibroblasts of patients to perform whole-exome sequencing, run a CDG-panel, or perform functional studies. We detected two patients with an increased trisialoTF isoform. Although the cause for this elevation is unknown, we believe