bims-meglyc 2026-09-27 papers

Issue of 2026–09–27
five papers selected by
Silvia Radenkovic, UMC Utrecht

Clin Chem. 2026 Sep 25. pii: hvag116. [Epub ahead of print]

Biomarker Discovery for PMM2-CDG Using Fractionated N-Glycomics Analysis.

Earnest J P Daniel, Andrew C Edmondson, Wenyue Zhang, Eva Morava, Mary Freeman, Hayden Vreugdenhill, Seishu Horikoshi, Christina Lam, Robin H J Kemperman, Stephen R Master, Hudson H Freeze, Miao He.

BACKGROUND: The most common congenital disorder of glycosylation (CDG) worldwide is phosphomannomutase 2‎ (PMM2)-CDG, which presents with a highly variable, multisystem clinical spectrum that poses challenges for diagnosis and prognosis.
MATERIALS AND METHODS: We performed N-glycomics analysis on plasma and 3 plasma fractions: affinity-purified transferrin, IgG, and a triple-depleted fraction in which IgG, transferrin, and albumin were removed. A total of 103 samples from 71 PMM2-CDG patients were analyzed.
RESULTS: Three major glycosylation abnormalities were identified in PMM2-CDG: (a) increases in intermediate glycans derived from high-mannose glycan assembly; (b) decreases in mature/processed multi-antennary N-glycans; and (c) abnormal fucosylation and branching. Total plasma N-glycan analysis demonstrated high clinical sensitivity and specificity, with increased Man3GlcNAc2 (Man3)/Man4-6, Man3/8-9, and Man5/8 ratios detected in all patients. Novel PMM2-CDG diagnostic biomarkers were also identified from this study, including increased Man4GlcNAc2 linkage isomers in plasma and novel hybrid glycans in the transferrin fraction. When correlated with the Nijmegen Progression CDG Rating Scale (NPCRS) in a diverse cohort age >2 years (n = 39; NPCRS 10-40), 11 glycans and 10 glycan ratios from total plasma and plasma fractions showed significant associations, providing strong candidates for use as disease biomarkers for PMM2-CDG.
CONCLUSIONS: We identified 35 plasma N-glycan biomarkers in a large cohort of patients with PMM2-CDG, identifying key glycans and glycan ratios that correlate with clinical severity. Utilizing fractionated N-glycan profiling enhanced these clinical correlations, demonstrating their strong prognostic value and promising application as surrogate biomarkers in clinical trials.

DOI: https://doi.org/10.1093/clinchem/hvag116

Biomolecules. 2026 Sep 09. pii: 1308. [Epub ahead of print]16(9):

Glycoproteomics and Functional Characterization of Novel Variants in Siblings with ALG1-CDG.

Dongzhi Wei, Hui Wang, Senlin Peng, Yu Huang, Ganglong Yang, Weijie Dong, Xiaodong Gao, Ning Wang.

Congenital disorders of glycosylation (CDGs) are a growing group of inborn errors caused by gene defects in glycan biosynthesis pathways. Genetic testing of two patients from the same family harboring ALG1-related CDG (ALG1-CDG) revealed heterozygous variations in the c.1129 A>C and c.1263+3 A>T. Although most CDGs with abnormal N-glycosylation can be detected by transferrin screening, Western blotting of serum transferrin from the two siblings did not reveal significant glycosylation deficiency. In this study, the biochemical phenotype and pathological molecular basis of the CDGs in the siblings were further explored. Analysis of the patients' ALG1 cDNA indicated that the associated heterozygous variants were c.1129 A>C (p.Met377Leu) and c.1188 T>A (p.Cys396X). Single-molecule real-time (SMRT) sequencing indicated that the variant frequencies of M377L and C396X were 50% and 36%, respectively. In addition, glycoproteomics analysis suggested that the glycoforms of transferrin were altered in the patients and that glycosylation site occupancy was decreased. It was also confirmed that N-glycosylation was altered in the patients' serum transferrin. Conserved amino acid variants of yeast Alg1 were recombinantly overexpressed, purified and subjected to an in vitro quantitative activity assay. The results showed that these variants caused a decrease in enzymatic activity, suggesting pathogenicity.

Keywords: ALG1; congenital disorders of glycosylation; glycoproteomics; molecular basis; splicing variant

DOI: https://doi.org/10.3390/biom16091308

Muscle Nerve. 2026 Sep 21.

Assessment of Lectin Staining Biomarkers for GNE Myopathy Gene Therapy.

Kristina M Sattler, Brian J Paleo, Mackenzie N Roth, Kara E Bradley, Megan N Winkler, Wakako Yoshioka, Ichizo Nishino, Christoph Lepper, Kelly E Crowe.

INTRODUCTION/AIMS: GNE myopathy (GNEM) is a rare, autosomal recessive disorder caused by mutations in the UDP-N-acetylglucosamine (GlcNAc) 2-epimerase/N-acetylmannosamine (ManNAc) kinase (GNE) gene, which encodes a required enzyme for sialic acid (SA) biosynthesis. Reduced SA production is associated with progressive skeletal muscle wasting, but robust molecular biomarkers of SA deficiency and therapeutic restoration remain lacking. As gene therapy for GNEM continues to advance, there is a critical need for biomarkers that enable early, objective assessment of therapeutic response that may precede detectable clinical improvements. Here, we systematically compare a panel of glycan-binding lectins to identify sensitive and robust biomarkers of SA deficiency and restoration in GNEM.
METHODS: We evaluated a panel of glycan-binding lectins for differential binding under altered sialylation using fluorescent staining and flow cytometry in a GNE-deficient cell model, followed by fluorescent lectin staining of skeletal muscle biopsies from GNEM and non-GNEM patients.
RESULTS: Subterminal lectins SBA, PNA, and VVA showed greater sensitivity to hyposialylation than terminal lectins. By flow cytometry, SBA and PNA increased 90.38- and 50.03-fold, respectively, in GNE-deficient cells and decreased 96.06% and 91.83% following GNE restoration. In GNEM muscle, PNA showed the greatest increase (5.3-fold) and most consistent discrimination from non-GNEM muscle.
DISCUSSION: PNA demonstrated the most robust and consistent performance across models, supporting its promise as a biomarker to reflect restoration of sialylation that would occur in skeletal muscle after GNEM gene therapy. Further validation in clinical samples will establish its utility as a pharmacodynamic biomarker.

Keywords: GNE myopathy; biomarker; gene therapy; lectin; sialic acid

DOI: https://doi.org/10.1002/mus.70404

Elife. 2026 Sep 22. pii: RP107170. [Epub ahead of print]14

Pathogenic O-GlcNAc dyshomeostasis is associated with cortical malformations and hyperactivity.

Florence Authier, Asad Jan, Islam Faress, Christian Stald Skoven, Iria Esperon-Abril, Shagana Tharmakulasingam Balasubramaniam, Kévin-Sébastien Coquelin, Jens R Nyengaard, Carsten Scavenius, Benedetta Attianese, Oscar G Sevillano-Quispe, Simon Fristed Eskildsen, Jesper Skovhus Thomsen, Brian Hansen, Daan M F van Aalten.

Missense variants in the O-GlcNAc transferase (OGT) gene have recently been shown to segregate with a syndromic form of intellectual disability (OGT-ID), underscoring the importance of protein O-GlcNAcylation in brain function. However, the underlying pathophysiological mechanisms linking ID to potential OGT malfunction-whether developmental, neurophysiological, or both - remain unclear. Here, we present comprehensive analyses encompassing behaviour and brain architecture of a rodent model carrying the pathogenic C921Y OGT-ID variant. These mice show a range of behavioural deficits, including hyperactivity, impulsivity, and associative learning phenotypes. Structural studies, using micro-computed tomography and magnetic resonance imaging, revealed reduced skull size, microcephaly, reduced cortical thickness and hypoplastic corpus callosum. Detailed histological analyses revealed dysplastic changes in the neocortex, predominantly affecting the superficial layers of the cingulate cortex. Mechanistically, quantitative proteomic analyses revealed O-GlcNAc dyshomeostasis associated with distinct perturbed molecular pathways involved in brain development. Taken together, these data reveal neurodevelopmental defects associated with O-GlcNAc dyshomeostasis and provide a platform for dissecting mechanism and treatments of OGT-ID.

Keywords: O-GlcNAc; O-glycosylation; behaviour; cortical dysplasia; intellectual disability; mouse; neurodevelopment; neuroscience

DOI: https://doi.org/10.7554/eLife.107170

Glycobiology. 2026 Sep 24. pii: cwag081. [Epub ahead of print]

Targeted Control of Protein O-GlcNAcylation in Living Cells.

Tongyang Xu, Billy Wai-Lung Ng.

O-linked N-acetylglucosamine glycosylation (O-GlcNAcylation) regulates many intracellular proteins, but linking a cellular phenotype to O-GlcNAcylation of a specific substrate remains difficult. Global perturbation of O-GlcNAc transferase (OGT) or O-GlcNAcase (OGA) changes many proteins at once and therefore provides limited information about individual substrates. Protein-selective approaches address this problem by directing OGT or OGA activity toward chosen proteins in living cells. Here, we review small-molecule recruiters, nanobody-based systems, inducible recruitment strategies, RNA aptamers, and complementary site-level approaches. We compare what each method can establish and the controls needed for interpretation, with particular attention to target engagement, target-protein O-GlcNAcylation, site assignment, selectivity, and functional validation. Together, these approaches provide increasingly direct ways to define how O-GlcNAcylation of individual proteins contributes to cellular function.

Keywords: O-GlcNAcylation; OGA; OGT; induced proximity; post-translational modification

DOI: https://doi.org/10.1093/glycob/cwag081