Publications | CDG Hub

September 2023

September 1, 2023

Genetic, serological and clinical evaluation of childhood myasthenia syndromes- single center subgroup analysis experience in Turkey

Özsoy Ö, et al. Acta Neurol Belg., September 1, 2023

Congenital myasthenic syndrome is a disease that occurs due to several types such as mutations in different pre-synaptic, synaptic, post-synaptic proteins and, glycosylation defects associated with congenital myopathy. Juvenile myasthenia gravis is an autoimmune condition usually caused by antibodies targeting the acetylcholine receptor. Our objective is to conduct an analysis on the subgroup traits exhibited by patients who have been diagnosed with congenital myasthenic syndrome and juvenile myasthenia gravis, with a focus on their long-term monitoring and management.

August 2023

August 29, 2023

Congenital disorders of glycosylation: narration of a story through its patents

Monticelli M, D'Onofrio T, Jaeken J, Morava E, Andreotti G, Cubellis MV. Orphanet J Rare Dis, August 29, 2023

Congenital disorders of glycosylation are a group of more than 160 rare genetic defects in protein and lipid glycosylation. Since the first clinical report in 1980 of PMM2-CDG, the most common CDG worldwide, research made great strides, but nearly all of them are still missing a cure. CDG diagnosis has been at a rapid pace since the introduction of whole-exome/whole-genome sequencing as a diagnostic tool. Here, we retrace the history of CDG by analyzing all the patents associated with the topic. To this end, we explored the Espacenet database, extracted a list of patents, and then divided them into three major groups: (1) Drugs/therapeutic approaches for CDG, (2) Drug delivery tools for CDG, (3) Diagnostic tools for CDG. Despite the enormous scientific progress experienced in the last 30 years, diagnostic tools, drugs, and biomarkers are still urgently needed.

August 23, 2023

Defining the phenotype of PGAP3-congenital disorder of glycosylation; a review of 65 cases

Altassan R, Allers MM, De Graef D, Shah R, de Vries M, Larson A, Glamuzina E, Morava E. Mol Genet Metab, August 23, 2023

Biallelic pathogenic variants in PGAP3 cause a rare glycosylphosphatidyl-inositol biogenesis disorder, PGAP3-CDG. This multisystem condition presents with a predominantly neurological phenotype, including developmental delay, intellectual disability, seizures, and hyperphosphatemia. Here, we summarized the phenotype of sixty-five individuals including six unreported individuals from our CDG natural history study with a confirmed PGAP3-CDG diagnosis. Common additional features found in this disorder included brain malformations, behavioral abnormalities, cleft palate, and characteristic facial features. This report aims to review the genetic and metabolic findings and characterize the disease's phenotype while highlighting the necessary clinical approach to improve the management of this rare CDG.

August 21, 2023

An oligogenic case of severe neonatal thrombocytopenia and a purportedly benign variant in GFI1B requiring reinterpretation

Frenkel M, Hall A, Meyn MS, Diamond CA. Platelets., August 21, 2023

Although thrombocytopenia in neonatal intensive care patients is rarely due to inherited disorders, the number of genetic variants implicated in platelet defects has grown dramatically with increasing genome-wide sequencing. Here we describe a case of severe, oligogenic neonatal thrombocytopenia and reinterpret a reportedly benign mutation that is likely pathogenic. Despite this patient's synonymous mutation (GFI1B 576 C>T, Phe192=) being annotated as benign, GFI1B is a well-known regulator of megakaryopoiesis, this variant alters splicing and megakaryocyte maturation, and our analysis of existing genome-wide associated studies demonstrates that it likely causes gray platelet syndrome.

August 17, 2023

Congenital diaphragmatic hernia in siblings with PIGA-related congenital disorder of glycosylation

Crenshaw MM, Thompson L, Piqué DG, Micke K, Saenz M, Baker PR 2nd. Am J Med Genet A . , August 17, 2023

There are over 150 proteins involved in glycosylphosphatidylinositol (GPI)-anchored protein biosynthesis, a class within the larger category of congenital disorders of glycosylation (CDG). Pathogenic variants identified in phosphatidylinositol glycan class A protein (PIGA) are associated with X-linked PIGA-CDG, a GPI-anchor defect. The disease has primarily been characterized by hypotonia, epilepsy, and global developmental delay; however, only 89 known cases are reported, so the phenotypic spectrum has likely not yet been fully delineated. Congenital diaphragmatic hernia (CDH) has been reported in patients with various GPI-anchor related defects but has only been described in one prior individual with PIGA-CDG. Here, we describe the second and third reported cases of CDH in two brothers with PIGA-CDG caused by a pathogenic missense variant in PIGA: c.355C > T, p.R119W.

August 9, 2023

Combined PMM2-CDG and hereditary fructose intolerance in a patient with mild clinical presentation

Hong X, Edmondson AC, Strong A, Pomerantz D, Michl E, Berry G, He M. Mol Genet Metab., August 9, 2023

We report a patient with an extremely rare, combined diagnosis of PMM2-CDG and hereditary fructose intolerance (HFI). By comparing with other patients, under-galactosylation was identified as a feature of HFI. Fructose/sorbitol/sucrose restriction was initiated right afterwards. The patient is at the mild end of the PMM2-CDG spectrum, raising the question of sorbitol's role in the pathogenesis of PMM2-CDG and whether fructose/sorbitol/sucrose restriction could benefit other PMM2-CDG patients. Additionally, epalrestat, an emerging potential PMM2-CDG therapy, may benefit HFI patients.

August 9, 2023

The multifaceted roles of the brain glycogen

Markussen KH, Corti M, Byrne BJ, Vander Kooi CW, Sun RC, Gentry MS. J Neurochem., August 9, 2023

Glycogen is a biologically essential macromolecule that is directly involved in multiple human diseases. While its primary role in carbohydrate storage and energy metabolism in the liver and muscle is well characterized, recent research has highlighted critical metabolic and non-metabolic roles for glycogen in the brain. In this review, the emerging roles of glycogen homeostasis in the healthy and diseased brain are discussed with a focus on advancing our understanding of the role of glycogen in the brain.

August 4, 2023

Interplay of Impaired Cellular Bioenergetics and Autophagy in PMM2-CDG

Ligezka AN, et al. Genes., August 4, 2023

Congenital disorders of glycosylation (CDG) and mitochondrial disorders are multisystem disorders with overlapping symptomatology. Pathogenic variants in the PMM2 gene lead to abnormal N-linked glycosylation. This disruption in glycosylation can induce endoplasmic reticulum stress, contributing to the disease pathology. Although impaired mitochondrial dysfunction has been reported in some CDG, cellular bioenergetics has never been evaluated in detail in PMM2-CDG. This prompted us to evaluate mitochondrial function and autophagy/mitophagy in vitro in PMM2 patient-derived fibroblast lines of differing genotypes from our natural history study.

August 4, 2023

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

Del Caño-Ochoa et al. J Inherit Metab Dis ., August 4, 2023

CAD is a large, 2,225 amino acid multi-enzymatic 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 non-specific, there is no biomarker, and the protein has over 1,000 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 7 affected individuals; they would benefit from uridine treatment. We also tested 9 variants previously reported as pathogenic and confirmed the damaging effect of 7.

August 1, 2023

Association between acute complications in PMM2-CDG patients and haemostasis anomalies: Data from a multicentric study and suggestions for acute management

Wicker C, et al. Mol Genet Metab., August 1, 2023

Patients with PMM2-CDG develop acute events (stroke-like episodes (SLEs), thromboses, haemorrhages, seizures, migraines) associated with both clotting factors (factor XI) and coagulation inhibitors (antithrombin, protein C and protein S) deficiencies. The aim of the study was to correlate acute events to haemostasis and propose practical guidelines.