Search Results (289)

Glutamine-Fructose-6-Phosphate Transaminase 1 (GFPT1), the rate-limiting enzyme of the hexosamine biosynthetic pathway (HBP), provides the UDP-N-acetylglucosamine (UDP-GlcNAc) required for protein glycosylation. Biallelic mutations in GFPT1 cause congenital myasthenic syndromes (GFPT1-CMS), yet the molecular mechanisms linking impaired glycosylation to skeletal muscle dysfunction remain incompletely understood. Here, we combine cellular models of inducible Gfpt1 knockdown and a skeletal muscle-specific Gfpt1 knockout mouse (Gfpt1^Tm1d/Tm1d) with whole-cell proteomics, immunoblot studies and secretomics to define glycosylation-dependent defects in intracellular trafficking, ER stress signaling and autophagy. Global proteomic profiling of Gfpt1-deficient myoblasts revealed marked downregulation of protein trafficking pathways and impaired secretion of key muscle cargo proteins, including serglycin (Srgn). Loss of GFPT1 reduced both high-molecular-weight glycosylated serglycin and its core protein, accompanied by intracellular retention and decreased secretion. These trafficking defects coincide with robust activation of the unfolded protein response (UPR), evidenced by increased Xbp1 expression and accumulation of spliced Xbp1s across pharmacologic, cellular, and mouse models of GFPT1 deficiency. Converging evidence from proteomics, immunoblotting, and immunofluorescence demonstrated impaired autophagy, including increased LC3-II accumulation, elevated p62/Sqstm1 levels, and enhanced p62-positive puncta in both Gfpt1-deficient C2C12 myoblasts and skeletal muscle. Soluble/insoluble fractionation further confirmed p62 accumulation, indicating defective autophagic flux and buildup of aggregated cargo. Together, these findings identify a glycosylation-dependent failure in protein trafficking that triggers ER stress, UPR activation, and autophagy impairment in Gfpt1-deficient skeletal muscle. This mechanistic cascade provides a unifying explanation for muscle pathology in GFPT1-CMS and suggests that restoring glycosylation or improving proteostasis may represent viable therapeutic approaches. Full article

Background and Objectives: Familial Mediterranean fever (FMF) is a hereditary autoinflammatory disease characterized by recurrent inflammatory attacks and a risk of AA amyloidosis. Although inflammatory activity may persist during attack-free periods, reliable biomarkers of subclinical inflammation remain limited. The pan-immune-inflammation value (PIV), a composite index derived from circulating immune cell counts, has emerged as a marker of systemic inflammation. This study investigated the association between PIV, MEFV mutation burden, and amyloidosis in patients with FMF during attack-free periods. Materials and Methods: This retrospective cross-sectional study included 386 adult patients with FMF followed at a tertiary rheumatology clinic. Patients were stratified by MEFV mutation status into three groups: Group 1 (genetically non-confirmatory FMF or low-penetrance/non-causative MEFV variants such as E148Q), Group 2 (single pathogenic mutation), and Group 3 (biallelic pathogenic mutations). Patients were also categorized by amyloidosis status. PIV was calculated as (neutrophil count × platelet count × monocyte count)/lymphocyte count using complete blood count parameters obtained during attack-free visits. Associations between PIV and clinical characteristics were evaluated using correlation and logistic regression analyses, and discriminative performance was assessed using receiver operating characteristic (ROC) curve analysis. Statistical significance was set at p < 0.05. Results: PIV levels differed significantly across genotype-defined groups (median: 172, 329.3, and 479.5 in Groups 1–3, respectively; p < 0.001) and were higher in patients with amyloidosis than in those without amyloidosis (540.5 vs. 218.1; p < 0.001). In multivariable logistic regression analysis, PIV remained independently associated with both biallelic pathogenic mutation status (OR = 1.007, 95% CI: 1.003–1.010, p < 0.001) and the presence of amyloidosis (OR = 1.002, 95% CI: 1.001–1.003, p < 0.001). ROC analysis showed an AUC of 0.853 for distinguishing Group 3 from Group 1 (cut-off 337; sensitivity 80.7%, specificity 77.0%) and an AUC of 0.814 for discriminating patients with and without amyloidosis (cut-off 316.4; sensitivity 86.0%, specificity 65.6%). Conclusions: PIV was independently associated with MEFV mutation burden and amyloidosis in patients with FMF during attack-free periods. These findings suggest that PIV may reflect the inflammatory burden associated with genetic mutation load and amyloidosis in FMF. Prospective longitudinal studies are warranted to externally validate these findings and further clarify the relationship between PIV, inflammatory burden, and disease severity in FMF. Full article

The CRISPR/Cas9 system has been widely used for gene editing in various species; however, mosaicism remains a significant challenge. This study aimed to improve gene editing efficiency and reduce mosaicism in porcine embryos by exploring double electroporation pre- and post-in vitro fertilization combined with zona pellucida (ZP) removal. We evaluated the effects of these treatments on the development and mutation rates of oocytes/zygotes edited with guide RNAs (gRNAs) targeting GGTA1, CMAH, or B4GALNT2 genes. Double electroporation significantly increased the total and biallelic mutation rates in ZP-intact zygotes but not in ZP-free zygotes edited using GGTA1-targeted gRNAs. All blastocysts from ZP-free zygotes exhibited biallelic mutations following double electroporation. For the CMAH gene, all blastocysts exhibited mutations (biallelic mutations ≥ 80%); however, double electroporation and ZP removal did not affect their mutation rates or efficiency. For the B4GALNT2 gene, double electroporation significantly increased total mutation rates in ZP-intact zygotes, whereas all blastocysts from ZP-free zygotes showed biallelic mutation. These findings suggest that double electroporation, particularly with ZP removal, may enhance gene-editing efficiency, reduce mosaicism and improve the success of genetic modifications. Full article

Enlarged vestibular aqueduct (EVA) is a common inner ear malformation that causes sensorineural hearing loss. It is frequently associated with pathogenic variants in the SLC26A4 gene. This study aimed to investigate the genetic basis of hearing loss in Mongolian patients with EVA. Whole-exome sequencing was performed in 19 Mongolian patients from 15 unrelated families diagnosed with EVA with or without cochlear incomplete partition type II. All patients underwent high-resolution computed tomography of the temporal bone to confirm the diagnosis. Biallelic SLC26A4 pathogenic variants were identified in all 15 families, achieving a 100% diagnostic yield. The most frequent variant was c.919-2A>G (40%), followed by c.2027T>A (23.3%) and c.1318A>T (16.7%). The spectrum of variants includes population-specific variants found in East Asians (c.919-2A>G), North Asians (c.2027T>A), and Southwest Asians (c.716T>A), suggesting a unique mutation spectrum in this Mongolian cohort characterized by variants prevalent across various Eurasian populations, which remains to be confirmed in larger studies. Furthermore, correlation analyses on multi-ethnic allele frequencies of biallelic SLC26A4 genotypes demonstrated positive correlations with deaf cohorts of East Asian, North Asian, Northeast Asian, and Western Asian groups. Digenic inheritance (with pathogenic variants in FOXI1, KCNJ10, or EPHA2) was not observed, and there was no clear genotype–phenotype correlation between specific SLC26A4 genotypes and hearing levels or inner ear malformations. This study provides a comprehensive overview of the genetic landscape of EVA in the Mongolian population. The identification of biallelic SLC26A4 pathogenic variants in all families underscores the clinical role of this gene in EVA pathogenesis. The observed pan-ethnic mutation spectrum likely reflects the genetic diversity resulting from historical migrations of Mongolians. Full article

Background/Objectives: Thrombocytopenia in chronic lymphocytic leukemia (CLL) is a heterogeneous and multifactorial complication that often reflects the combined effects of immune dysregulation, impaired megakaryopoiesis, bone marrow microenvironmental disruption, and disease-related factors. In patients with high-risk molecular features, particularly TP53 abnormalities, management becomes increasingly challenging and frequently refractory to conventional therapies. Methods: We report a 57-year-old male with long-standing CLL characterized by a highly aggressive and treatment-refractory course. The patient developed persistent severe thrombocytopenia despite multiple lines of therapy, including corticosteroids, intravenous immunoglobulin, rituximab, splenectomy, and thrombopoietin receptor agonists. Subsequent treatments with ibrutinib and a venetoclax-based regimen failed to improve platelet counts and were discontinued due to worsening cytopenia. Bone marrow evaluation, molecular/cytogenetic analyses, and subsequent treatment responses were thoroughly evaluated. Results: Bone marrow evaluation revealed hypercellularity with significant CLL infiltration, dysplastic megakaryopoiesis, and reticulin fibrosis, indicating impaired platelet production in addition to immune-mediated destruction. Molecular and cytogenetic analyses demonstrated high-risk disease with deletion of 17p and dual TP53 mutations (p.His179Tyr and p.Arg282Trp), consistent with biallelic TP53 disruption. Romiplostim monotherapy did not result in a meaningful hematologic response. However, following the addition of idelalisib, a rapid and sustained increase in platelet counts was observed, allowing tapering of romiplostim and stabilization of hematologic parameters. Conclusions: This case highlights the complex and dynamic pathophysiology of thrombocytopenia in CLL, where immune-mediated destruction and defective thrombopoiesis coexist within a profoundly altered marrow microenvironment. TP53 disruption appears to play a central role not only in driving treatment resistance but also in promoting immune dysregulation and disease aggressiveness. Although a delayed therapeutic effect of romiplostim cannot be entirely excluded, the distinct temporal association following idelalisib initiation suggests a potential collaborative interaction or disease-directed clearance that may facilitate platelet recovery in this setting. Refractory thrombocytopenia in CLL should be approached as a manifestation of complex disease biology rather than an isolated complication. This single observation indicates that in TP53 aberrant cases with multi-mechanism thrombocytopenia, disease-directed targeted therapy may contribute significantly to platelet recovery. Full article

Background and Clinical Significance: SWI/SNF chromatin remodeling complex-deficient malignancies constitute an aggressive group of undifferentiated tumors defined by inactivation of core subunits including SMARCA4 (BRG1) or SMARCB1 (INI1). In the head and neck, these tumors predominate in the sinonasal tract; oral cavity presentations are exceedingly rare, with reported cases predominantly representing metastatic disease. Peri-implant gingival masses in clinical practice are overwhelmingly reactive, but their occasional malignant nature mandates timely biopsy and thorough pathologic workup. We report the first comprehensively molecularly characterized case of a peri-implant gingival SWI/SNF complex-deficient tumor with confirmed biallelic SMARCA4 inactivation. Case Presentation: A 75-year-old man presented with a one-week history of a rapidly enlarging exophytic erythematous peri-implant gingival mass in the right posterior mandible (region 44–47). Incisional biopsy demonstrated an undifferentiated high-grade tumor with epithelioid, plasmablastoid, and focally rhabdoid morphology with necrosis. Immunohistochemistry showed complete loss of BRG1 (SMARCA4) with retained INI1 (SMARCB1), EMA positivity, Ki-67 of approximately 100%, and negativity across all lineage-specific markers (hematolymphoid, epithelial, melanocytic, endothelial, squamous). Comprehensive next-generation sequencing (Oncomine Comprehensive Assay Plus) confirmed biallelic SMARCA4 inactivation via a truncating nonsense mutation (p.Trp1346Ter; VAF 73.85%) combined with copy number loss, establishing the molecular mechanism underlying BRG1 protein loss. Co-occurring alterations included homozygous CDKN2A/CDKN2B deletion, MTAP loss (9p21.3), clonal TP53 and KEAP1 mutations, and intermediate–high tumor mutational burden (13.3 mutations/Mb) with microsatellite stability. The patient initiated carboplatin–paclitaxel and achieved a partial response at one month with further shrinkage by four months. This case illustrates a rare oral cavity manifestation of SWI/SNF complex deficiency arising in a peri-implant location, with a diagnostic workup that required integration of immunohistochemistry and molecular profiling for definitive characterization. The MTAP deletion co-occurring with homozygous CDKN2A/B loss identifies a potentially actionable synthetic lethal vulnerability to MAT2A and PRMT5 inhibitors currently under clinical investigation. An occult primary site could not be fully excluded due to absence of a dedicated staging workup. Conclusions: Rapidly enlarging peri-implant gingival masses should prompt timely biopsy and SWI/SNF marker testing when histology is high-grade and lineage-ambiguous. NGS-based molecular profiling confirms diagnosis, elucidates mechanism, and reveals actionable targets in this rare tumor class. Full article

Background: Autosomal recessive intellectual developmental disorder-13 (MRT13; OMIM #613192) is a rare neurodevelopmental disorder caused by pathogenic variants in TRAPPC9. Most reported variants are single-nucleotide variants (SNVs), small insertions/deletions, or copy number variants (CNVs), whereas complex structural variants (SVs) remain poorly characterized. Objectives: This study sought to review the clinical and molecular spectrum of TRAPPC9-related disorder, harmonize reported variants, explore genotype–phenotype correlations, and expand the mutational spectrum by reporting a novel patient with a cryptic SV. Methods: We report a novel patient whose diagnostic workup included array-CGH, whole-exome sequencing, karyotyping, and optical genome mapping. Additionally, a systematic literature search was primarily conducted in PubMed/MEDLINE from 2009 to January 2026, with Embase, Web of Science, Google Scholar, Orphanet, OMIM, and ClinVar used as supplementary sources. Patients carrying pathogenic/likely pathogenic TRAPPC9 variants were included. Clinical and molecular data were extracted and descriptively summarized. Genotype–phenotype correlations were explored. Reported variants were re-annotated using MANE Select reference transcripts. Results: The reported patient showed biallelic TRAPPC9 disruption due to two independently inherited structural variants: a maternal ~35 kb intragenic deletion involving exons 10–12, identified by 400K array-CGH, and a paternal balanced translocation t(4;8) disrupting TRAPPC9 within intron 8, characterized by trio-OGM and paired-end whole-genome sequencing (PE-WGS). Thirty-one studies reporting 75 previously published patients were included in the literature review; together with the novel patient described here, the final cohort comprised 76 patients. Intellectual disability was present in 100% of cases, followed by brain MRI abnormalities (95.9%), microcephaly (82.3%), motor delay (71.4%), dysmorphic features (69.8%), obesity (52.8%), behavioral abnormalities/autism spectrum disorder (49.2%/43.8%), and epilepsy (15.9%). Most patients (84.2%) harbored homozygous variants. Thirty-two distinct sequence variants were identified, predominantly loss-of-function. CNVs were identified in 13.2% of patients. No genotype–phenotype correlations were identified. Conclusions: The systematic review provides an updated and harmonized overview of the clinical and molecular spectrum of TRAPPC9-related disorder, supporting the presence of a recognizable phenotype and confirming the predominance of loss-of-function variants. Our case further highlights the contribution of cryptic structural variants to the mutational spectrum of TRAPPC9 and the diagnostic value of advanced genomic approaches. Full article

APR-246 (Eprenetapopt) is a small-molecule drug that restores the activity of dysfunctional p53 proteins caused by missense mutations that affect the DNA-binding domain. However, recent studies suggest that APR-246 can also induce cell death in cancer cells that carry wild-type (WT) TP53. Here, we aimed to determine the impact of APR-246 on the survival of acute myeloid leukemia (AML) cells using isogenic Molm13 cells that harbor WT TP53, a missense mutation of TP53^R175H, or a biallelic deletion of TP53 (TP53^−/−). Our results showed that Molm13 TP53^−/− cells were significantly more resistant to APR-246-induced cell death compared with their Molm13 TP53^R175H/− mutant and Molm13 TP53^+/+ counterparts. In addition, knockdown of TP53 significantly reduced cytotoxicity induced by APR-246 in two TP53 WT AML cell lines (MV4-11 and OCI-AML2). Moreover, APR-246 markedly decreased the clonogenicity of TP53 WT hematopoietic stem/progenitor cells (HSPCs) isolated from humans and mice. In contrast, biallelic loss of TP53, but not TP53 missense mutation, significantly increased the resistance of mouse HSPCs to APR-246. Mechanistically, the loss of functional p53 proteins in Molm13 and MV4-11 cells decreased intrinsic apoptosis and impaired the production of cellular reactive oxygen species (ROS) induced by APR-246. Together, our results indicate that, in at least a subset of AML cell lines and normal HSPCs, APR-246-induced ROS production and cytotoxicity are enhanced in the presence of WT p53 proteins. Full article

TANGO2-deficiency disorder (TDD) is a rare autosomal recessive condition characterised by neurodevelopmental delay, TANGO2 spells, life-threatening metabolic crises, and cardiac arrhythmias. Genotype–phenotype correlations remain poorly defined and the neurobehavioural profile of affected individuals is largely unexplored. We conducted a retrospective multicentre study of five Italian patients with genetically confirmed TDD, identified between June 2023 and May 2025. Clinical, neurophysiological, neuroimaging, genetic, and neurodevelopmental data were collected. Adaptive functioning, cognitive ability, and behavioural profiles were assessed using standardised instruments. All five patients carried biallelic TANGO2 mutations, including two previously unreported variants. Clinical severity ranged from an asymptomatic individual under preventive therapy to a fatal early-onset metabolic crisis. Marked intrafamilial variability was observed in two siblings sharing the same genotype. Systematic neurodevelopmental assessment revealed a spectrum of cognitive and adaptive outcomes, with attentional difficulties identified as a recurrent feature. No metabolic crises or TANGO2 spells were documented following initiation of B-vitamin and cofactor supplementation in surviving patients. This cohort expands the mutational and phenotypic spectrum of TDD and highlights the diagnostic value of TANGO2 testing in patients with neurodevelopmental delay or paroxysmal neurological episodes, even in the absence of metabolic crises. Early supplementation therapy may contribute to clinical stability, though prospective controlled studies are needed. Full article

Mulibrey nanism is a rare autosomal recessive multisystem disorder caused by biallelic loss of function variants in TRIM37 encoding a peroxisomal E3 ubiquitin ligase. Initially described in Finland, where it remains most prevalent due to a founder mutation, the condition is now recognized worldwide and is characterized by severe prenatal-onset growth failure, distinctive craniofacial features, radiological abnormalities, ocular findings, and hepatopathy. Although its clinical spectrum extends far beyond these core manifestations, the major determinant of morbidity and mortality is progressive cardiovascular disease, including constrictive pericarditis and restrictive cardiomyopathy. Additional features include metabolic dysfunction such as insulin resistance and type 2 diabetes, gonadal insufficiency, skeletal abnormalities including fibrous dysplasia, and an increased risk of benign and malignant tumours. The clinical course evolves across the lifespan from early growth and developmental abnormalities to progressive multisystem disease in adolescence and adulthood. Recent advances have expanded understanding of TRIM37 function, linking it to mTORC1 TFEB signalling autophagy, centrosome integrity, extracellular matrix regulation, and immune cell function, providing mechanistic insights into tumour predisposition, skeletal pathology, and immune dysregulation. Management remains supportive and requires multidisciplinary care with emphasis on early recognition and treatment of cardiac disease, metabolic complications, and malignancy risk. Prognosis is variable but improves with early diagnosis and appropriate surveillance. This review summarises the clinical spectrum molecular mechanisms and current management of Mulibrey nanism and highlights priorities for future research. Full article

Prominin-1 (Prom1/CD133) has long been recognized as a structural determinant of photoreceptor outer segment (OS) morphogenesis, yet rapidly accumulating evidence extends its role to retinal pigment epithelium (RPE) homeostasis, encompassing autophagy–lysosomal flux, outer segment phagocytosis, mitochondrial function, and regulation of inflammatory stress. This review synthesizes mechanistic and transcriptomic insights that position PROM1 as a central regulator of photoreceptor and RPE integrity, reframing Prom1 disease as a multi-compartment retinal disorder relevant to both inherited retinal dystrophies (IRDs) and atrophic age-related macular degeneration (aAMD). We develop a dual-axis conceptual model in which Prom1 dysfunction can initiate pathology in either the photoreceptors (OS morphogenesis failure) or the RPE, including impaired autophagic flux, lysosomal activity, defective phagocytosis, and Epithelial-Mesenchymal Transition (EMT)-like de-differentiation, with secondary cross-compartmental degeneration. Clinically, autosomal-dominant missense variants associate with macular or cone-rod dystrophy, whereas biallelic truncating/splice-site mutations drive early-onset rod–cone disease and panretinal/RPE atrophy, illustrating genotype–phenotype diversity. By integrating recent high-resolution transcriptomic data from Prom1-deficient RPE cells with long-standing insights into photoreceptor biology, we highlight converging pathways of degeneration that challenge a photoreceptor-centric view and unify disparate phenotypes within a single molecular framework. These insights broaden the therapeutic landscape, advancing gene augmentation and pathway-targeted strategies to preserve RPE integrity, sustain photoreceptor function, and modify disease course in PROM1-associated IRDs and atrophic AMD. Full article

Background/Objectives: Multiple epiphyseal dysplasia (MED) is a clinically and genetically heterogeneous group of disorders characterized by a waddling gait, joint pain, and early-onset osteoarthritis. The aim of this study was to compare the genetic characteristics and long-term clinical follow-up findings of 22 patients with MED from 17 unrelated families. Methods: Molecular diagnosis was performed using clinical exome analysis and exome sequencing. Seventeen children were followed for a median of 5.5 years. Results: Eighteen disease-related variants were identified: 47% in COMP, 11.8% each in COL9A2 and COL9A3 in a monoallelic state, 17.6% in SLC26A2, and 11.8% each in MATN3 and CANT1 in a biallelic state. Some COMP mutations previously identified in pseudoachondroplasia, an allelic disorder of MED1, were shown in our study to exhibit a typical MED1 or intermediate phenotype. In contrast, it was confirmed that certain mutations in SLC26A2 lead to MED4 phenotype. Furthermore, it has been observed that biallelic variants in MATN3 may be associated with the MED5 phenotype. In patients with MED2 and MED3, the knee joint is affected, while in other types, the hip joint is predominantly affected. In 15 children followed until ages 11–18, height decreased slightly as they grew older but remained normal or at the lower limit, and slow progression was observed in the waddling gait and joint pain, except in the intermediate form. Conclusions: This study reveals the frequency of disease-related variants, including seven novel ones, in genes leading to MED1–5 and 7 phenotypes, and expands the spectrum of genetic and clinical phenotypes. Full article

Background/Objectives: Inherited retinal diseases (IRDs) represent a genetically heterogeneous group of disorders caused by mutations in over 280 genes with more than 3100 identified variants. While gene-specific replacement therapies have achieved landmark success with voretigene neparvovec (Luxturna) for biallelic RPE65-associated retinal dystrophy, developing individual therapies for each genetic subtype remains impractical. This review examines gene-agnostic therapeutic approaches utilizing neuroprotection and immunomodulation that target common pathophysiological mechanisms shared across multiple IRD genotypes. Methods: We reviewed the literature on neuroprotective and immunomodulatory gene therapy strategies for IRDs, focusing on neurotrophic factors and complement system modulation. Results: Neuroprotective approaches delivering neurotrophic factors—including pigment epithelium-derived factor (PEDF), ciliary neurotrophic factor (CNTF), rod-derived cone viability factor (RdCVF), brain-derived neurotrophic factor (BDNF), fibroblast growth factors (FGFs), glial cell line-derived neurotrophic factor (GDNF), and proinsulin—have demonstrated photoreceptor preservation across multiple preclinical IRD models regardless of the underlying genetic mutation. The recent FDA approval of CNTF cell-based gene therapy (Encelto) for macular telangiectasia type 2 validates this therapeutic paradigm. Complement system inhibition represents another gene-agnostic strategy, with intravitreal complement inhibitors approved for geographic atrophy secondary to age-related macular degeneration and gene therapy approaches targeting C3, C5, or delivering soluble complement regulators under investigation for IRDs. Combination strategies simultaneously addressing multiple pathogenic pathways may offer synergistic benefits. Conclusions: Gene-agnostic approaches targeting neuroprotection and immunomodulation offer a therapeutic paradigm capable of benefiting patients across the spectrum of IRD genotypes, potentially transforming treatment for conditions where mutation-specific therapies remain unavailable. Full article

Background: Marinesco–Sjögren syndrome (MSS, MIM #248800) is a condition that is characterized by biallelic pathogenic variants in the SIL1 gene. Manifestations include congenital cataracts, cerebellar ataxia, progressive muscle weakness and skeletal deformities, delay in psychomotor development, hypergonadotropic hypogonadism and short stature. Muscular involvement has been extensively discussed as a clinical finding but there is little literature on muscle imaging. The aim of this paper is to systematically review muscular imaging techniques in MSS reported in the literature, and to describe the clinical and imaging features of two pediatric subjects with MSS. Methods: Having searched through three electronic databases (PubMed, Scopus and Web of Science) two articles, written in English, describing twelve patients with MSS mutations on whom muscle MRI imaging was performed, were selected. In addition, two paediatric cases (brother and sister) with Marinesco–Sjögren syndrome (MSS) and MRI muscle findings were added. Data on type of study, cohort characteristics, type of mutation, neuromuscular signs and symptoms, imaging assessment, electrophysiological findings, biopsies, CNS symptoms, ocular signs and muscle imaging data were collected and stored in a table. Results: Of the 239 articles examined, only 3 used a muscle imaging technique to describe myopathy in MSS; one used a CT while another a muscle MRI. All 14 patients showed signs of fatty replacement. The infiltration mainly affected the lower limbs, but involvement in the upper limb was described in some adult patients. Conclusions: Performing a muscle MRI in MSS can lead to the early identification of muscle involvement and may be a useful biomarker to monitor disease progression. Full article

Glycosylation depends on luminal nucleotide sugars delivered by solute carrier 35 (SLC35) transporters. SLC35A3 is a uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) transporter. In humans, biallelic mutations in SLC35A3 cause arthrogryposis, mental retardation, and seizures (AMRS). To define how loss of SLC35A3 function reshapes the neural glycome, we profiled N-, O-, and glycosaminoglycans (GAGs) in Slc35a3 knockout mouse brains. N- and O-glycans were analyzed by MALDI-TOF MS, and GAG disaccharides were quantified by anion-exchange HPLC. Knockout mouse brains exhibited attenuation of complex-type N-glycans with a reciprocal rise in high-mannose species, as revealed by MALDI-TOF MS profiling. In contrast, ConA lectin blotting showed no significant change, consistent with its preferential detection of mannose-rich glycans. Branching analysis revealed loss of tri- and tetra-antennary structures compared with biantennary species. O-glycan profiling showed core-2-type species (Hex₂HexNAc₂ backbone) decreased. The dominant disialyl core-1 remained stable. Total GAG output (chondroitin/dermatan sulfate, heparan sulfate, and hyaluronan) was preserved. These findings support a microdomain model in which SLC35A3 acts as a locally effective supplier of UDP-GlcNAc to MGAT4 (branching N-acetylglucosaminyltransferase that installs the β1,4-GlcNAc arm) in the brain, while alternative routes buffer UDP-GlcNAc delivery for GAG and mucin-type O-glycan biosynthesis. Accordingly, AMRS may be attributed to impaired higher-order N-glycan branching in the brain. Full article