Toward understanding tissue-specific symptoms in dolichol-phosphate-mannose synthesis disorders; insight from DPM3-CDG

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Screening for abnormal glycosylation in a cohort of adult liver disease patients

Congenital Disorders of Glycosylation (CDG) are a rapidly expanding group of rare genetic defects in glycosylation. In a novel CDG subgroup of Vacuolar-ATPase assembly defects various degrees of hepatic injury have been described, including end stage liver disease. However, the CDG diagnostic workflow can be complex as liver disease per se may be associated with abnormal glycosylation. Therefore, we collected serum samples of patients with a wide range of liver pathology to study the performance and yield of two CDG screening methods. Our aim was to identify glycosylation patterns that could help to differentiate between primary and secondary glycosylation defects in liver disease. To this end, we analyzed serum samples of 1042 adult liver disease patients. This cohort consisted of 567 liver transplant candidates and 475 chronic liver disease patients. Our workflow consisted of screening for abnormal glycosylation by transferrin isoelectric focusing (tIEF), followed by in-depth analysis of the abnormal samples with quadruple time-of-flight mass spectrometry (QTOF-MS). Screening with tIEF resulted in identification of 247 (26%) abnormal samples. QTOF-MS analysis of 110 of those did not reveal glycosylation abnormalities comparable with those seen in V-ATPase assembly factor deficiencies. However, two patients presented with isolated sialylation deficiency. Fucosylation was significantly increased in liver transplant candidates compared to healthy controls and patients with chronic liver disease. In conclusion, a significant percentage of patients with liver disease presented with abnormal CDG screening results, however, not indicative for a V-ATPase assembly factor defect. Advanced glycoanalytical techniques assist in the dissection of secondary and primary glycosylation defects. This article is protected by copyright. All rights reserved

Характеристика диагностики врожденных нарушений гликозилирований у 40 подозреваемые больных из Молдовы

Institute of Mother and Child, Chisinau, Republic of Moldova, Translational Metabolic Laboratory, RadboudUMC, Nijmegen, Netherlands, “N. Testemitanu” State University of Medicine and Pharmacy, Chisinau, Republic of Moldova, “Petru Poni” Institute of Macromolecular Chemistry, Romanian Academy, Iasi, Romania, “C.D. Nenitescu” Centre of Organic Chemistry, Romanian Academy, Bucharest, RomaniaIntroducere: Erorile în sinteza, asamblarea și / sau procesarea glicanilor provoacă o familie de patologii genetice grupate într-o unitate nosologică sub denumirea de Deraglări Congenitale ale Glicozilării (CDG), actualmente fiind descrise în jur de 150 de tipuri. În orice stare clinică inexplicabilă este necesar de suspectat CDG, în special în cazul afectărilor multisistemice cu implicare neurologică. Metoda obișnuită pentru diagnosticarea CDG este investigarea transferinei serice prin focalizare izoelectrică (IEF). Scopul: Diagnosticul CDG la pacienții suspecți cu simptome de afectare multisistemică, bazată pe screeningul transferinei serice prin focalizare izoelectrică. Materiale și metode: În studiul prezent au fost utilizate probe de ser recoltate de la 40 de pacienți cu vârste variate (2 luni - 15 ani) suspectați pentru CDG, care aveau hipotonie, convulsii, retard psihoneuromotor, caracteristici dismorfice cu implicare multisistemică. Pentru diagnosticul CDG, IEF al transferinei serice a fost efectuat în colaborare cu RadboudUMC, Nijmegen, Olanda. În unele cazuri, s-a utilizat tratamentul cu neuraminidază pentru a detecta polimorfismul genetic al transferinei care poate imita structura anormală a glicanului. În plus, s-a efectuat spectroscopia RMN a urinei pacienților cercetaţi pentru diagnosticarea erorilor înnăscute de metabolism, care pot imita un profil caracteristic pentru CDG. Rezultate: Ca urmare a screeningului selectiv, 37 de pacienți aveau un profil normal al transferinei, în timp ce 3 probe au fost identificate cu profil anormal, sugestiv pentru CDG I. Galactozemia, fructozemia, alcoolismul pot exprima același profil de IEF ca și pentru CDG I. Probele celor trei pacienți au fost analizate prin metode biochimice și molecular-genetice care au identificat că la un pacient paternul anormal IEF a transferinei a fost cauzat de galactozemie, în timp ce la un altul de fructozemie. În cazul celui de-al treilea pacient rezultatele sugerează prezența CDG I și necesită o analiză avansată a profilului glicomic prin spectroscopia de masă. Concluzie: Focalizarea izoelectrică a transferrinei este instrumentul principal pentru diagnosticul CDG pentru multe laboratoare de screening datorită eficienței crescute la preţ rezonabil, în comparație cu alte metode.Введение: Нарушения синтеза, сборки и/или процессинга гликанов являются причиной группы генетических патологий метаболизма, называемых врождёнными нарушениями гликозилирования (ВНГ), типов которых на данный момент описано около 150. ВНГ следует подозревать при любой необъяснённой клинической патологии, особенно с полиорганным поражением с вовлечением нервной системы. Обычный метод диагностики ВНГ – исследование трансферрина в сыворотке крови методом изоэлектрического фокусирования (ИЭФ). Цель: Представление результатов ИЭФ трансферрина сыворотки крови 40 пациентов с полиорганными поражениями, с подозрением на ВНГ. Материалы и методы: В представленном исследовании использовались сыворотки 40 педиатрических пациентов с подозрением на ВНГ, различного возраста (2 мес – 15 лет), с гипотонией, судорогами, задержкой психомоторного развития, признаками дизморфизма, нарушениями развития с полиорганной патологией. Для диагностики ВНГ ИЭФ трансферрина сыворотки производилось в сотрудничестве с RadboudUMC, Неймеген, Нидерланды. B некоторых случаях, использовалось лечение нейраминидазой с целью обнаружения генетического полиморфизма трансферрина. Результаты: В результате селективного скрининга обнаружено, что у 37 пациентов с подозрением на ВНГ был нормальный профиль трансферрина, а в 3 образцах был обнаружен аномальный профиль, говорящий о возможности ВНГ I. К сожалению, анализ трансферрина методом ИЭФ имеет некоторые ограничения, в связи с фактом, что при галактоземии, фруктоземии и алкоголизме может обнаруживаться такой же профиль, как и при ВНГ I. Таким образом, данные пациенты были проанализированы с использованием биохимических и молекулярно-генетических методов, обнаруживших, что у одного пациента аномальный профиль ИЭФ трансферрина вызван галактоземией, а у другого пациента – фруктоземией. Последний пациент успешно прощёл данный тест, что говорит о наличии ВНГ I и необходимости определения профиля гликомики. Заключение: ИЭФ трансферрина представляет собой основное средство диагностики ВНГ во многих лабораториях скрининга, в связи с экономической эффективностью по сравнению с другими методам

Congenital disorder of glycosylation caused by starting site-specific variant in syntaxin-5

Mutations in genes critical for proper intra-Golgi transport can cause human syndromes due to defects in glycosylation of proteins. Here, the authors identify a human variant of Syntaxin-5 that causes fatal multisystem disease and mislocalization of glycosyltransferases due to altered Golgi transport

Synergistic use of glycomics and single-molecule molecular inversion probes for identification of congenital disorders of glycosylation type-1

Congenital disorders of glycosylation type 1 (CDG-I) comprise a group of 27 genetic defects with heterogeneous multisystem phenotype, mostly presenting with nonspecific neurological symptoms. The biochemical hallmark of CDG-I is a partial absence of complete N-glycans on transferrin. However, recent findings of a diagnostic N-tetrasaccharide for ALG1-CDG and increased high-mannose N-glycans for a few other CDG suggested the potential of glycan structural analysis for CDG-I gene discovery. We analyzed the relative abundance of total plasma N-glycans by high resolution quadrupole time-of-flight mass spectrometry in a large cohort of 111 CDG-I patients with known (n = 75) or unsolved (n = 36) genetic cause. We designed single-molecule molecular inversion probes (smMIPs) for sequencing of CDG-I candidate genes on the basis of specific N-glycan signatures. Glycomics profiling in patients with known defects revealed novel features such as the N-tetrasaccharide in ALG2-CDG patients and a novel fucosylated N-pentasaccharide as specific glycomarker for ALG1-CDG. Moreover, group-specific high-mannose N-glycan signatures were found in ALG3-, ALG9-, ALG11-, ALG12-, RFT1-, SRD5A3-, DOLK-, DPM1-, DPM3-, MPDU1-, ALG13-CDG, and hereditary fructose intolerance. Further differential analysis revealed high-mannose profiles, characteristic for ALG12- and ALG9-CDG. Prediction of candidate genes by glycomics profiling in 36 patients with thus far unsolved CDG-I and subsequent smMIPs sequencing led to a yield of solved cases of 78% (28/36). Combined plasma glycomics profiling and targeted smMIPs sequencing of candidate genes is a powerful approach to identify causative mutations in CDG-I patient cohorts

Autosomal Recessive Dilated Cardiomyopathy due to DOLK Mutations Results from Abnormal Dystroglycan O-Mannosylation

Genetic causes for autosomal recessive forms of dilated cardiomyopathy (DCM) are only rarely identified, although they are thought to contribute considerably to sudden cardiac death and heart failure, especially in young children. Here, we describe 11 young patients (5–13 years) with a predominant presentation of dilated cardiomyopathy (DCM). Metabolic investigations showed deficient protein N-glycosylation, leading to a diagnosis of Congenital Disorders of Glycosylation (CDG). Homozygosity mapping in the consanguineous families showed a locus with two known genes in the N-glycosylation pathway. In all individuals, pathogenic mutations were identified in DOLK, encoding the dolichol kinase responsible for formation of dolichol-phosphate. Enzyme analysis in patients' fibroblasts confirmed a dolichol kinase deficiency in all families. In comparison with the generally multisystem presentation in CDG, the nonsyndromic DCM in several individuals was remarkable. Investigation of other dolichol-phosphate dependent glycosylation pathways in biopsied heart tissue indicated reduced O-mannosylation of alpha-dystroglycan with concomitant functional loss of its laminin-binding capacity, which has been linked to DCM. We thus identified a combined deficiency of protein N-glycosylation and alpha-dystroglycan O-mannosylation in patients with nonsyndromic DCM due to autosomal recessive DOLK mutations

Variation in general supportive and preventive intensive care management of traumatic brain injury: a survey in 66 neurotrauma centers participating in the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study

Abstract Background General supportive and preventive measures in the intensive care management of traumatic brain injury (TBI) aim to prevent or limit secondary brain injury and optimize recovery. The aim of this survey was to assess and quantify variation in perceptions on intensive care unit (ICU) management of patients with TBI in European neurotrauma centers. Methods We performed a survey as part of the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study. We analyzed 23 questions focused on: 1) circulatory and respiratory management; 2) fever control; 3) use of corticosteroids; 4) nutrition and glucose management; and 5) seizure prophylaxis and treatment. Results The survey was completed predominantly by intensivists (n = 33, 50%) and neurosurgeons (n = 23, 35%) from 66 centers (97% response rate). The most common cerebral perfusion pressure (CPP) target was > 60 mmHg (n = 39, 60%) and/or an individualized target (n = 25, 38%). To support CPP, crystalloid fluid loading (n = 60, 91%) was generally preferred over albumin (n = 15, 23%), and vasopressors (n = 63, 96%) over inotropes (n = 29, 44%). The most commonly reported target of partial pressure of carbon dioxide in arterial blood (PaCO2) was 36–40 mmHg (4.8–5.3 kPa) in case of controlled intracranial pressure (ICP) < 20 mmHg (n = 45, 69%) and PaCO2 target of 30–35 mmHg (4–4.7 kPa) in case of raised ICP (n = 40, 62%). Almost all respondents indicated to generally treat fever (n = 65, 98%) with paracetamol (n = 61, 92%) and/or external cooling (n = 49, 74%). Conventional glucose management (n = 43, 66%) was preferred over tight glycemic control (n = 18, 28%). More than half of the respondents indicated to aim for full caloric replacement within 7 days (n = 43, 66%) using enteral nutrition (n = 60, 92%). Indications for and duration of seizure prophylaxis varied, and levetiracetam was mostly reported as the agent of choice for both seizure prophylaxis (n = 32, 49%) and treatment (n = 40, 61%). Conclusions Practice preferences vary substantially regarding general supportive and preventive measures in TBI patients at ICUs of European neurotrauma centers. These results provide an opportunity for future comparative effectiveness research, since a more evidence-based uniformity in good practices in general ICU management could have a major impact on TBI outcome

Variation in neurosurgical management of traumatic brain injury

Background: Neurosurgical management of traumatic brain injury (TBI) is challenging, with only low-quality evidence. We aimed to explore differences in neurosurgical strategies for TBI across Europe. Methods: A survey was sent to 68 centers participating in the Collaborative European Neurotrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study. The questionnaire contained 21 questions, including the decision when to operate (or not) on traumatic acute subdural hematoma (ASDH) and intracerebral hematoma (ICH), and when to perform a decompressive craniectomy (DC) in raised intracranial pressure (ICP). Results: The survey was completed by 68 centers (100%). On average, 10 neurosurgeons work in each trauma center. In all centers, a neurosurgeon was available within 30 min. Forty percent of responders reported a thickness or volume threshold for evacuation of an ASDH. Most responders (78%) decide on a primary DC in evacuating an ASDH during the operation, when swelling is present. For ICH, 3% would perform an evacuation directly to prevent secondary deterioration and 66% only in case of clinical deterioration. Most respondents (91%) reported to consider a DC for refractory high ICP. The reported cut-off ICP for DC in refractory high ICP, however, differed: 60% uses 25 mmHg, 18% 30 mmHg, and 17% 20 mmHg. Treatment strategies varied substantially between regions, specifically for the threshold for ASDH surgery and DC for refractory raised ICP. Also within center variation was present: 31% reported variation within the hospital for inserting an ICP monitor and 43% for evacuating mass lesions. Conclusion: Despite a homogeneous organization, considerable practice variation exists of neurosurgical strategies for TBI in Europe. These results provide an incentive for comparative effectiveness research to determine elements of effective neurosurgical care