Jos Jansen

112 Chapter 5 The primary aim of this study was to identify glycosylation patterns that could help to differentiate between primary and secondary glycosylation defects in liver disease within a cohort of adult patients with end-stage liver disease. As a secondary aim, we studied to what extent liver disease affects CDG screening. Materials and methods Selection of liver disease patients, sample selection and ethical considerations We collected 1042 samples from patients with an established chronic liver disease from four Dutch tertiary referral hospitals. (Figure 2) Samples were collected in the period 1993 to 2013. We specifically targeted ESLD patients who were evaluated and waitlisted for LTx. These samples were provided by Erasmus MC in Rotterdam (n= 264), LUMC in Leiden (n=142) and UMCG in Groningen (n=155). All samples were drawn and aliquoted preceding LTx. Chronic liver disease samples (n=410), without ESLD, were provided by the Radboudumc in Nijmegen and by the LUMC (n=65, all with a diagnosis of auto-immune hepatitis). These patients were seen at the outpatient clinic for diagnosis and treatment of a range of liver diseases. Patients with viral hepatitis (infectious hepatitis B, C or E) were excluded from analysis as we hypothesized that the presence of underlying CDG would be unlikely in this patient population. Samples from healthy controls (n=40) were obtained from the local bloodbank. All samples were stored at − 80 °C till analysis. Material was collected in agreement with the Dutch code of conduct for responsible use of human tissue (Dutch Federation of Biomedical Scientific Societies, www.federa.org ). All experiments were performed in accordance with the guidelines and regulations of the Ethics Committee of the Radboudumc. Approval was documented in case file 2018-5012. Study design and workflow We first performed tIEF of the collected samples to identify global N-glycosylation defects with hyposialylation. Sixty-one samples were excluded prior to tIEF: 24 samples because they were drawn after liver transplantation, 21 were of very poor quality and unsuitable for further workup, 5 samples were wrongly allocated, 10 patients were < 18 years of age at time of sampling and one sample was from a patient with an established diagnosis of CDG.