Quality of life in children with erythropoietic protoporphyria:a case-control study

Erythropoietic protoporphyria (EPP) is an inherited metabolic disease that causes painful phototoxic reactions, starting in childhood. Studies have shown a reduced quality of life (QoL) in adults with EPP, however, data on children with the disease are lacking. Since treatment for EPP is currently not registered for children, knowledge about their QoL is of crucial importance. In this prospective, case–control study, we included children from the Netherlands and Belgium diagnosed with EPP and matched to healthy controls. Previously collected EPP quality of life (EPP-QoL) data from matched adults with EPP were used. QoL scores, utilizing the Pediatric Quality of Life Inventory (PedsQL) and the disease-specific EPP-QoL, were collected. Scores range from 0 to 100, with higher scores indicating a higher QoL. Non-parametric tests were used to compare groups. A total of 15 cases, 13 matched healthy control children, and 15 matched adults with EPP were included. Children with EPP exhibited lower median scores in the PedsQL in both physical (cases: 87.5 (interquartile range [IQR] 77.7–96.1), controls: 99.2 [IQR 94.9–100.0], p = 0.03) and social (cases: 77.5 [IQR 69.4–86.3], controls: 97.5 [IQR 78.8–100.0], p = 0.04) domains compared to healthy children, although these differences were not statistically significant after correcting for multiple testing. The overall median EPP-QoL score for children was similar to adults with EPP (children: 44.4 [IQR 25.0–54.2], adults: 45.8 [IQR 25.7–68.1], p = 0.68). However, within the EPP-QoL subdomain on QoL, children were found to have significantly lower median scores (children: 16.7 [IQR 0.0–33.3], adults: 33.3 [IQR 33.3–62.5], p &lt; 0.01). In conclusion, children with EPP experience a reduced QoL compared to both healthy children and adults with EPP. Ensuring treatment availability for this patient group is crucial for improving their QoL. We advocate the inclusion of children in safety and efficacy studies, to ensure availability of treatment in the future.</p

Quality of life in children with erythropoietic protoporphyria:a case-control study

Erythropoietic protoporphyria (EPP) is an inherited metabolic disease that causes painful phototoxic reactions, starting in childhood. Studies have shown a reduced quality of life (QoL) in adults with EPP, however, data on children with the disease are lacking. Since treatment for EPP is currently not registered for children, knowledge about their QoL is of crucial importance. In this prospective, case–control study, we included children from the Netherlands and Belgium diagnosed with EPP and matched to healthy controls. Previously collected EPP quality of life (EPP-QoL) data from matched adults with EPP were used. QoL scores, utilizing the Pediatric Quality of Life Inventory (PedsQL) and the disease-specific EPP-QoL, were collected. Scores range from 0 to 100, with higher scores indicating a higher QoL. Non-parametric tests were used to compare groups. A total of 15 cases, 13 matched healthy control children, and 15 matched adults with EPP were included. Children with EPP exhibited lower median scores in the PedsQL in both physical (cases: 87.5 (interquartile range [IQR] 77.7–96.1), controls: 99.2 [IQR 94.9–100.0], p = 0.03) and social (cases: 77.5 [IQR 69.4–86.3], controls: 97.5 [IQR 78.8–100.0], p = 0.04) domains compared to healthy children, although these differences were not statistically significant after correcting for multiple testing. The overall median EPP-QoL score for children was similar to adults with EPP (children: 44.4 [IQR 25.0–54.2], adults: 45.8 [IQR 25.7–68.1], p = 0.68). However, within the EPP-QoL subdomain on QoL, children were found to have significantly lower median scores (children: 16.7 [IQR 0.0–33.3], adults: 33.3 [IQR 33.3–62.5], p &lt; 0.01). In conclusion, children with EPP experience a reduced QoL compared to both healthy children and adults with EPP. Ensuring treatment availability for this patient group is crucial for improving their QoL. We advocate the inclusion of children in safety and efficacy studies, to ensure availability of treatment in the future.</p

Beyond genetics: Deciphering the impact of missense variants in CAD deficiency

16 páginas, 5 figuras, 1 tablaCAD is a large, 2225 amino acid multienzymatic protein required for de novo pyrimidine biosynthesis. Pathological CAD variants cause a developmental and epileptic encephalopathy which is highly responsive to uridine supplements. CAD deficiency is difficult to diagnose because symptoms are nonspecific, there is no biomarker, and the protein has over 1000 known variants. To improve diagnosis, we assessed the pathogenicity of 20 unreported missense CAD variants using a growth complementation assay that identified 11 pathogenic variants in seven affected individuals; they would benefit from uridine treatment. We also tested nine variants previously reported as pathogenic and confirmed the damaging effect of seven. However, we reclassified two variants as likely benign based on our assay, which is consistent with their long-term follow-up with uridine. We found that several computational methods are unreliable predictors of pathogenic CAD variants, so we extended the functional assay results by studying the impact of pathogenic variants at the protein level. We focused on CAD's dihydroorotase (DHO) domain because it accumulates the largest density of damaging missense changes. The atomic-resolution structures of eight DHO pathogenic variants, combined with functional and molecular dynamics analyses, provided a comprehensive structural and functional understanding of the activity, stability, and oligomerization of CAD's DHO domain. Combining our functional and protein structural analysis can help refine clinical diagnostic workflow for CAD variants in the genomics era.This work was supported by grant RTI2018-098084-B-I00 financed by MCIN/AEI/10.13039/501100011033/ and “FEDER Unamanera de hacer Europa,” by grant PID2021-128468NBI00 financed by MCIN/AEI/10.13039/501100011033 and by a grant from Fundacion Ram on Areces Ciencias de la Vida (XX National Call) to SR-M. FdC-O is a postdoctoral 1182 del CAÑO-OCHOA ET AL. 15732665, 2023, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/jimd.12667 by Csic Organización Central Om (Oficialia Mayor) (Urici), Wiley Online Library on [13/11/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License fellow of the Generalitat Valenciana (APOSTD 2021). AR-d-C is supported by salary from the European Commission–Next Generation EU through the CSIC Global Health Platform (PTI+ Salud Global) established by EU Council Regulation 2020/2094. HHF, BN, and SMP were supported by The Rocket Fund, R01DK099551, and U54 NS115198. SMP is also supported by a training component of U54 NS115198. MPW is supported by an MSCA Individual Fellowship (894669) and an FWO Senior Postdoctoral Fellowship (1289023N). X-ray diffraction experiments at synchrotrons were done through the participation of SR-M in the BAG proposals 2017082302, 2018082950, 2019093709, 2020074406, 2021075216, and 2022075911 at ALBA, and MX-2076, MX-2351, and MX-2452 at European Synchrotron Radiation Facility. The authors thank the ALBA synchrotron staff and Max H. Nanao at beamtime ID23-2 at the ESRF synchrotron for assistance.Peer reviewe

International consensus guidelines for phosphoglucomutase 1 deficiency (PGM1-CDG): Diagnosis, follow-up, and management

P. W. is supported by the Clinical Research Fund, University Hospitals Leuven, Leuven, Belgium. This work is partially funded by the grant titled Frontiers in Congenital Disorders of Glycosylation (1U54NS115198-01) from the National Institute of Neurological Diseases and Stroke (NINDS), the National Center for Advancing Translational Sciences (NCATS), and the Rare Disorders Consortium Research Network (RDCRN) (E. M., K. R., C. F., H. F., C. L., and A. E.)Phosphoglucomutase 1 (PGM1) deficiency is a rare genetic disorder that affects glycogen metabolism, glycolysis, and protein glycosylation. Previously known as GSD XIV, it was recently reclassified as a congenital disorder of glycosylation, PGM1-CDG. PGM1-CDG usually manifests as a multisystem disease. Most patients present as infants with cleft palate, liver function abnormalities and hypoglycemia, but some patients present in adulthood with isolated muscle involvement. Some patients develop life-threatening cardiomyopathy. Unlike most other CDG, PGM1-CDG has an effective treatment option, d-galactose, which has been shown to improve many of the patients' symptoms. Therefore, early diagnosis and initiation of treatment for PGM1-CDG patients are crucial decisions. In this article, our group of international experts suggests diagnostic, follow-up, and management guidelines for PGM1-CDG. These guidelines are based on the best available evidence-based data and experts' opinions aiming to provide a practical resource for health care providers to facilitate successful diagnosis and optimal management of PGM1-CDG patients.preprintpublishe

Congenital Disorders of Glycosylation: The Next Generation

Glycosylation is one of the most abundant protein modifications found in nature. It results from a meticulously orchestrated process involving numerous proteins for the assembly and modification of oligosaccharide chains, and their attachment onto proteins and lipids. The importance of glycosylation is illustrated by a group of diseases called Congenital Disorders of Glycosylation (CDG). To date, almost 100 distinct disorders have been identified encompassing defects in N- and O-linked protein glycosylation, but also in the synthesis of GPI-anchors and glycolipids. Considering the possibility to screen for most deficiencies in protein N-glycosylation by means of isoelectric focusing of serum transferrin, the project focused on this group of disorders. The genetic heterogeneity of CDG, but also the phenotypic overlap between the different disorders is remarkable. A clinical ‘hit and run’ diagnosis forms thus rather the exception than the rule. Therefore, patients with a biochemically proven glycosylation deficiency remain often without a molecular diagnosis. In this study, we aimed to circumvent the bottleneck of a gene by gene approach through the implementation of massive parallel sequencing techniques in as well CDG research as diagnostics (Chapter 3). For the elucidation of novel CDG, whole exome sequencing was performed in 24 individuals with a presumed deficiency in the N-linked glycosylation pathway (Chapter 4 and 5). Once the genetic defect was identified, its pathogenic nature was confirmed using cell biological assays. In this way, a genetic diagnosis could be obtained in nine patients (i.e. 38%), while the most likely candidate gene is still under investigation in seven additional cases (i.e. 30%). In parallel, a targeted assay for a panel of 79 genes was developed to improve CDG diagnostics (Chapter 6). Over a period of two years, the panel was used for molecular testing in a total number of 86 patients with a presumed deficiency in the N-linked glycosylation pathway. A final molecular diagnosis could be obtained in 38 of them (i.e. 44%). Based on these results, we proposed a tentative novel flowchart wherein a patient considered to have CDG first enters a diagnostic setting for gene panel testing. A close collaboration between the diagnostic and research department would then allow those patients, in whom the culprit gene could not be identified or in whom the pathogenicity of a variant needs to be verified, to subsequently enter a research setting for further biochemical testing. During this study, mutations in MAN1B1 were identified to cause a novel CDG-II. The biochemical characteristics of the index case allowed for the rapid identification of 18 additional patients (Chapter 7). All cases displayed a similar phenotype characterized by intellectual disability, delayed motor and speech development, hypotonia, macrocephaly and truncal obesity. During the time span of this PhD project, the intracellular localization of MAN1B1 became the subject of a still ongoing debate. Indeed, besides its role in N-glycan processing, the α(1,2)-mannosidase has been proposed to act as a key factor in ER quality control by targeting terminally misfolded proteins for proteasomal degradation. Since all mediators of ERAD are assumed to reside within the ER, it only seemed natural that MAN1B1 would execute its function within the same organelle. However, today opinions are changing. While some researchers still believe that MAN1B1 resides within the ER, others are convinced that the enzyme localizes to a presumed ERQC compartments or resides within the Golgi apparatus. In Chapter 9, we could clearly demonstrate that the endogenous MAN1B1 in primary skin fibroblasts is localized within the Golgi apparatus, thereby confirming the initial –but still controversial– results of Sifers and coworkers. Our findings were further supported by the observation that MAN1B1 deficient fibroblasts display an aberrant Golgi morphology in the absence of an ER stress response (i.e. UPR or unfolded protein response) (Chapter 8 and 9). While former studies mainly focused on the effect of MAN1B1 deficiency on the fate of misfolded cargo, we investigated –with respect to the phenotype– the effect on secretory proteins that attained their native folding state (Chapter 9). In this way, we could demonstrate that MAN1B1 deficiency does not only enable the intracellular accumulation and partial secretion of nonnative proteins, but in addition impairs the anterograde trafficking of the properly folded cargo. In Chapter 10 of this manuscript, we assumed that the aforementioned accumulation of (mis-)folded proteins within the Golgi apparatus could overwhelm the capacity of the secretory pathway, thereby generating a primary Golgi stress response. Through several pilot experiments we could show that MAN1B1 deficiency generates a mild to moderate transcriptional response that was not only uniformly present among the different patients, but that also differed from the responses observed in other CDG-II cell lines. However, additional investigations are necessary to further address the extent of a possible Golgi stress response in MAN1B1-CDG and to understand how this transcriptional response might impact patient management.List of abbreviations_9 Part 1: An extensive review of glycosylation and its diseases_15 Chapter 1: From glycosylation to CDG and back_17 Glycosylation in general_19 N-linked protein glycosylation_33 Diseases of glycosylation_48 Chapter 2: Aims of the study_67 Part 2: The Next Generation - Massive parallel sequencing in CDG_71 Chapter 3: How to identify novel CDG in the 21st century_73 Chapter 4: Exome sequencing for the identificatioin of novel CDG_89 Chapter 5: Beyond the exome_119 Chapter 6: A targeted approach to improve CDG diagnostics_137 Part 3: MAN1B1 deficiency - The elucidation of a novel CDG-II_155 Chapter 7: MAN1B1-CDG - A frequent cause of CDG-II_157 Chapter 8: The assumed function of MAN1B1_179 Chapter 9: From Golgi localization to alterations in the secretory pathway_197 Chapter 10: Is the Golgi stressed out (and why is the ER not)?_217 Part 4: General discussion_239 Chapter 11: From glycosylation to a next generation of CDG_241 Summary_255 Appendices_261 Table A_263 Curriculum vitae_273 Acknowledgements_281nrpages: 288status: publishe

Congenital disorders of glycosylation: other causes of ichthyosis

status: publishe

Clinical and Molecular Characterization of Classical-Like Ehlers-Danlos Syndrome Due to a Novel TNXB Variant

The Ehlers-Danlos syndromes (EDS) constitute a clinically and genetically heterogeneous group of connective tissue disorders. Tenascin X (TNX) deficiency is a rare type of EDS, defined as classical-like EDS (clEDS), since it phenotypically resembles the classical form of EDS, though lacking atrophic scarring. Although most patients display a well-defined phenotype, the diagnosis of TNX-deficiency is often delayed or overlooked. Here, we described an additional patient with clEDS due to a homozygous null-mutation in the TNXB gene. A review of the literature was performed, summarizing the most important and distinctive clinical signs of this disorder. Characterization of the cellular phenotype demonstrated a distinct organization of the extracellular matrix (ECM), whereby clEDS distinguishes itself from most other EDS subtypes by normal deposition of fibronectin in the ECM and a normal organization of the α5β1 integrin

Clinical and Molecular Characterization of Classical-Like Ehlers-Danlos Syndrome Due to a Novel TNXB Variant

The Ehlers-Danlos syndromes (EDS) constitute a clinically and genetically heterogeneous group of connective tissue disorders. Tenascin X (TNX) deficiency is a rare type of EDS, defined as classical-like EDS (clEDS), since it phenotypically resembles the classical form of EDS, though lacking atrophic scarring. Although most patients display a well-defined phenotype, the diagnosis of TNX-deficiency is often delayed or overlooked. Here, we described an additional patient with clEDS due to a homozygous null-mutation in the TNXB gene. A review of the literature was performed, summarizing the most important and distinctive clinical signs of this disorder. Characterization of the cellular phenotype demonstrated a distinct organization of the extracellular matrix (ECM), whereby clEDS distinguishes itself from most other EDS subtypes by normal deposition of fibronectin in the ECM and a normal organization of the α5β1 integrin