Biallelic variants in SNUPN cause a limb girdle muscular dystrophy with myofibrillar-like features.

Alterations in RNA-splicing are a molecular hallmark of several neurological diseases, including muscular dystrophies where mutations in genes involved in RNA metabolism or characterised by alterations in RNA splicing have been described. Here, we present five patients from two unrelated families with a limb-girdle muscular dystrophy (LGMD) phenotype carrying a biallelic variant in SNUPN gene. Snurportin-1, the protein encoded by SNUPN, plays an important role in the nuclear transport of small nuclear ribonucleoproteins (snRNPs), essential components of the spliceosome. We combine deep phenotyping, including clinical features, histopathology and muscle magnetic resonance image (MRI), with functional studies in patient-derived cells and muscle biopsies to demonstrate that variants in SNUPN are the cause of a new type of LGMD according to current definition. Moreover, an in vivo model in Drosophila melanogaster further supports the relevance of Snurportin-1 in muscle. SNUPN patients show a similar phenotype characterised by proximal weakness starting in childhood, restrictive respiratory dysfunction and prominent contractures, although interindividual variability in terms of severity even in individuals from the same family was found. Muscle biopsy showed myofibrillar-like features consisting of myotilin deposits and Z-disc disorganisation. MRI showed predominant impairment of paravertebral, vasti, sartorius, gracilis, peroneal and medial gastrocnemius muscles. Conservation and structural analyses of Snurportin-1 p.Ile309Ser variant suggest an effect in nuclear-cytosol snRNP trafficking. In patient-derived fibroblasts and muscle, cytoplasmic accumulation of snRNP components is observed, while total expression of Snurportin-1 and snRNPs remains unchanged, which demonstrates a functional impact of SNUPN variant in snRNP metabolism. Furthermore, RNA-splicing analysis in patients' muscle showed widespread splicing deregulation, in particular in genes relevant for muscle development and splicing factors that participate in the early steps of spliceosome assembly. In conclusion, we report that SNUPN variants are a new cause of limb girdle muscular dystrophy with specific clinical, histopathological and imaging features, supporting SNUPN as a new gene to be included in genetic testing of myopathies. These results further support the relevance of splicing-related proteins in muscle disorders.

The FGF14 GAA repeat expansion in Greek patients with late-onset cerebellar ataxia and an overview of the SCA27B phenotype across populations.

A pathogenic GAA repeat expansion in the first intron of the fibroblast growth factor 14 gene (FGF14) has been recently identified as the cause of spinocerebellar ataxia 27B (SCA27B). We herein screened 160 Greek index cases with late-onset cerebellar ataxia (LOCA) for FGF14 repeat expansions using a combination of long-range PCR and bidirectional repeat-primed PCRs. We identified 19 index cases (12%) carrying a pathogenic FGF14 GAA expansion, a diagnostic yield higher than that of previously screened repeat-expansion ataxias in Greek LOCA patients. The age at onset of SCA27B patients was 60.5 ± 12.3 years (range, 34-80). Episodic onset (37%), downbeat nystagmus (32%) and vertigo (26%) were significantly more frequent in FGF14 expansion-positive cases compared to expansion-negative cases. Beyond typical cerebellar signs, SCA27B patients often displayed hyperreflexia (47%) and reduced vibration sense in the lower extremities (42%). The frequency and phenotypic profile of SCA27B in Greek patients was similar to most other previously studied populations. We conclude that FGF14 GAA repeat expansions are the commonest known genetic cause of LOCA in the Greek population and recommend prioritizing testing for FGF14 expansions in the diagnostic algorithm of patients with LOCA.

Serum Neurofilament Light Chain in Replication Factor Complex Subunit 1 CANVAS and Disease Spectrum.

BACKGROUND: Biallelic intronic AAGGG repeat expansions in the replication factor complex subunit 1 (RFC1) gene were identified as the leading cause of cerebellar ataxia, neuropathy, vestibular areflexia syndrome. Patients exhibit significant clinical heterogeneity and variable disease course, but no potential biomarker has been identified to date. OBJECTIVES: In this multicenter cross-sectional study, we aimed to evaluate neurofilament light (NfL) chain serum levels in a cohort of RFC1 disease patients and to correlate NfL serum concentrations with clinical phenotype and disease severity. METHODS: Sixty-one patients with genetically confirmed RFC1 disease and 48 healthy controls (HCs) were enrolled from six neurological centers. Serum NfL concentration was measured using the single molecule array assay technique. RESULTS: Serum NfL concentration was significantly higher in patients with RFC1 disease compared to age- and-sex-matched HCs (P < 0.0001). NfL level showed a moderate correlation with age in both HCs (r = 0.4353, P = 0.0020) and patients (r = 0.4092, P = 0.0011). Mean NfL concentration appeared to be significantly higher in patients with cerebellar involvement compared to patients without cerebellar dysfunction (27.88 vs. 21.84 pg/mL, P = 0.0081). The association between cerebellar involvement and NfL remained significant after controlling for age and sex (ß = 0.260, P = 0.034). CONCLUSIONS: Serum NfL levels are significantly higher in patients with RFC1 disease compared to HCs and correlate with cerebellar involvement. Longitudinal studies are warranted to assess its change over time.

Cenobamate in patients with highly refractory focal epilepsy: A retrospective real-world study.

PURPOSE: To determine the effectiveness and safety outcomes of cenobamate in a cohort of patients with highly refractory focal epilepsy in routine clinical practice. METHODS: Observational, retrospective, phase 4 study on subjects receiving cenobamate in three Spanish centers. The primary endpoint was the retention rate at the last follow-up. The main secondary endpoints were the 50%-responder  and seizure-free rates at three months and the last follow-up. Other secondary endpoints were Global Clinical Impressions-Improvement (CGI-I) scores and treatment-emergent adverse events (TEAEs). RESULTS: Fifty-one patients with highly refractory focal epilepsy with 24.7 years of disease evolution, ten previously tried ASM, and a 23.5% of previous epilepsy surgery were included. The retention rate at the last follow-up was 80.4%. The 50% responder rate in focal seizures at three months was 56.5% (median reduction per month 51%, 0-74.6; p < 0.0001) and in focal to bilateral tonic-clonic seizures was 63.6% (median reduction per month 89%, 0-100; p = 0.022). A total of 54.3% of subjects reported a reduction in the intensity of focal seizures, and 66% manifested clinically significant satisfaction. Cenobamate allowed a significant decrease in concomitant ASM, especially sodium channel blockers. TEAEs were reported in 43.1% of individuals, 85% of whom resolved or improved, with no new safety findings. CONCLUSION: In this analysis of patients with highly refractory focal epilepsy treated with cenobamate according to standard clinical practice, there was evidence of a high reduction in both seizure frequency and intensity, with a manageable safety profile.

Frequency of GAA-FGF14 Ataxia in a Large Cohort of Brazilian Patients With Unsolved Adult-Onset Cerebellar Ataxia.

Objectives: Intronic FGF14 GAA repeat expansions have recently been found to be a common cause of hereditary ataxia (GAA-FGF14 ataxia; SCA27B). The global epidemiology and regional prevalence of this newly reported disorder remain to be established. In this study, we investigated the frequency of GAA-FGF14 ataxia in a large cohort of Brazilian patients with unsolved adult-onset ataxia. Methods: We recruited 93 index patients with genetically unsolved adult-onset ataxia despite extensive genetic investigation and genotyped the FGF14 repeat locus. Patients were recruited across 4 different regions of Brazil. Results: Of the 93 index patients, 8 (9%) carried an FGF14 (GAA)≥250 expansion. The expansion was also identified in 1 affected relative. Seven patients were of European descent, 1 was of African descent, and 1was of admixed American ancestry. One patient carrying a (GAA)376 expansion developed ataxia at age 28 years, confirming that GAA-FGF14 ataxia can occur before the age of 30 years. One patient displayed episodic symptoms, while none had downbeat nystagmus. Cerebellar atrophy was observed on brain MRI in 7 of 8 patients (87%). Discussion: Our results suggest that GAA-FGF14 ataxia is a common cause of adult-onset ataxia in the Brazilian population, although larger studies are needed to fully define its epidemiology.

Frequency and phenotypic spectrum of spinocerebellar ataxia 27B and other genetic ataxias in a Spanish cohort of late-onset cerebellar ataxia.

BACKGROUND AND PURPOSE: Dominantly inherited GAA repeat expansions in the fibroblast growth factor 14 (FGF14) gene have recently been shown to cause spinocerebellar ataxia 27B (SCA27B). We aimed to study the frequency and phenotype of SCA27B in a cohort of patients with unsolved late-onset cerebellar ataxia (LOCA). We also assessed the frequency of SCA27B relative to other genetically defined LOCAs. METHODS: We recruited a consecutive series of 107 patients with LOCA, of whom 64 remained genetically undiagnosed. We screened these 64 patients for the FGF14 GAA repeat expansion. We next analysed the frequency of SCA27B relative to other genetically defined forms of LOCA in the cohort of 107 patients. RESULTS: Eighteen of 64 patients (28%) carried an FGF14 (GAA)≥250 expansion. The median (range) age at onset was 62.5 (39-72) years. The most common clinical features included gait ataxia (100%) and mild cerebellar dysarthria (67%). In addition, episodic symptoms and downbeat nystagmus were present in 39% (7/18) and 37% (6/16) of patients, respectively. SCA27B was the most common cause of LOCA in our cohort (17%, 18/107). Among patients with genetically defined LOCA, SCA27B was the main cause of pure ataxia, RFC1-related disease of ataxia with neuropathy, and SPG7 of ataxia with spasticity. CONCLUSION: We showed that SCA27B is the most common cause of LOCA in our cohort. Our results support the use of FGF14 GAA repeat expansion screening as a first-tier genetic test in patients with LOCA.

Spheresomes are the main extracellular vesicles in low-grade gliomas.

Cancer progression and its impact on treatment response and prognosis is deeply regulated by tumour microenvironment (TME). Cancer cells are in constant communication and modulate TME through several mechanisms, including transfer of tumour-promoting cargos through extracellular vesicles (EVs) or oncogenic signal detection by primary cilia. Spheresomes are a specific EV that arise from rough endoplasmic reticulum-Golgi vesicles. They accumulate beneath cell membrane and are released to the extracellular medium through multivesicular spheres. This study describes spheresomes in low-grade gliomas using electron microscopy. We found that spheresomes are more frequent than exosomes in these tumours and can cross the blood-brain barrier. Moreover, the distinct biogenesis processes of these EVs result in unique cargo profiles, suggesting different functional roles. We also identified primary cilia in these tumours. These findings collectively contribute to our understanding of glioma progression and metastasis.

Optimized testing strategy for the diagnosis of GAA-FGF14 ataxia/spinocerebellar ataxia 27B.

Dominantly inherited GAA repeat expansions in FGF14 are a common cause of spinocerebellar ataxia (GAA-FGF14 ataxia; spinocerebellar ataxia 27B). Molecular confirmation of FGF14 GAA repeat expansions has thus far mostly relied on long-read sequencing, a technology that is not yet widely available in clinical laboratories. We developed and validated a strategy to detect FGF14 GAA repeat expansions using long-range PCR, bidirectional repeat-primed PCRs, and Sanger sequencing. We compared this strategy to targeted nanopore sequencing in a cohort of 22 French Canadian patients and next validated it in a cohort of 53 French index patients with unsolved ataxia. Method comparison showed that capillary electrophoresis of long-range PCR amplification products significantly underestimated expansion sizes compared to nanopore sequencing (slope, 0.87 [95% CI, 0.81 to 0.93]; intercept, 14.58 [95% CI, - 2.48 to 31.12]) and gel electrophoresis (slope, 0.84 [95% CI, 0.78 to 0.97]; intercept, 21.34 [95% CI, - 27.66 to 40.22]). The latter techniques yielded similar size estimates. Following calibration with internal controls, expansion size estimates were similar between capillary electrophoresis and nanopore sequencing (slope: 0.98 [95% CI, 0.92 to 1.04]; intercept: 10.62 [95% CI, - 7.49 to 27.71]), and gel electrophoresis (slope: 0.94 [95% CI, 0.88 to 1.09]; intercept: 18.81 [95% CI, - 41.93 to 39.15]). Diagnosis was accurately confirmed for all 22 French Canadian patients using this strategy. We also identified 9 French patients (9/53; 17%) and 2 of their relatives who carried an FGF14 (GAA)≥250 expansion. This novel strategy reliably detected and sized FGF14 GAA expansions, and compared favorably to long-read sequencing.

Impact on functional outcome of an adaptive Stroke Unit based system of care for patients undergoing endovascular treatment during pandemic times.

Introduction: The COVID19 pandemic collapsed intensive care units (ICUs) all around the world, conditioning systems of care (SOC) for other critical conditions such as severe ischemic stroke requiring endovascular treatment (EVT). Our aim was to evaluate the impact of an adaptive Stroke Unit (SU) based SOC on functional outcomes, with the goal of avoiding both general anesthesia (GA) and ICU admission in stroke patients treated with EVT. Material and methods: We performed an observational study comparing data from our traditional ICU-GA based SOC and the adaptive SU-Conscious Sedation (CS) based SOC (consecutive patients undergoing EVT 1 year prior and after onset of the pandemic). Primary outcome was 90-days modified Rankin Scale (mRS), and secondary outcomes included, among others, in-hospital complications, and hospital length of stay (LOS). Results: A total of 210 EVT were performed during the study period (107 under the traditional-SOC and 103 under the adaptive-SOC). A significantly greater proportion of patient was treated under CS (15.9% vs 57.3%; p < 0.001) and admitted for post-procedural care at SU (15% vs 66%; p < 0.001) in the adaptive SOC. Rates of in-hospital complications were similar in both periods, with reduced hospital LOS in the adaptive SOC (10 (7-15) vs 8 (6-12); p = 0.005). The adaptive SOC was associated with higher odds for 90 days favorable outcome (mRS 0-2) (aOR 3.15 (1.34-7.39); p = 0.008). Conclusion: In our case, an adaptive SOC that combined both preference for CS and postprocedural care in SU was associated with better functional outcomes and reduced healthcare resource use for patients undergoing EVT.

Frequency, Predictors, Etiology, and Outcomes for Deep Intracerebral Hemorrhage without Hypertension.

OBJECTIVES: Some patients with deep intracerebral hemorrhage (ICH) have a transient hypertensive response and they may be erroneously classified as secondary to hypertension. We investigated frequency, risk factors, and outcomes for patients with deep ICH without hypertension. MATERIALS AND METHODS: We consecutively recruited patients with spontaneous ICH attending two Spanish stroke centers (January 2015-June 2019). Excluded were patients with lobar/infratentorial ICH and patients who died during hospitalization. We defined deep ICH without hypertension when the bleeding was in a deep structure, no requirement for antihypertensive agents during follow-up and no evident chronic hypertension markers evaluated by transthoracic echocardiography, 24 h ambulatory blood pressure monitoring and/or electrocardiography. We compared clinical, radiological, and 3-month functional outcome data for deep-ICH patients with hypertension versus those without hypertension. RESULTS: Of 759 patients with ICH, 219 (mean age 69.6 ± 15.4 years, 54.8% men) met the inclusion criteria and 36 (16.4%) did not have hypertension. Of these 36 patients, 19 (52.7%) had a transient hypertensive response. Independent predictors of deep ICH without hypertension were age (adjusted OR:0.94;95%CI:0.91-0.96) and dyslipidemia (adjusted OR:0.27;95% CI:0.08-0.85). One third of deep ICH without hypertension were secondary to vascular malformations. Favorable outcomes (modified Rankin Scale 0-2) were more frequent in patients with deep ICH without hypertension compared to those with hypertension (70.9% vs 33.8%; p < 0.001). CONCLUSION: Of patients with deep ICH, 16.4% were unrelated with hypertension, around half showed hypertensive response, and around a third had vascular malformations. We suggest studying hypertension markers and performing a follow-up brain MRI in those patients with deep ICH without prior hypertension.

Supporting Evidence of Human Enteric Nervous System Adult Neurogenesis: Presence of Primary Cilia and Adult Neurogenesis Markers.

Adult neurogenesis has been profusely studied in central nervous system. However, its presence in enteric nervous system remains elusive although it has been recently demonstrated in mice and intimately linked to glial cells. Moreover, primary cilium is an important organelle in central adult neurogenesis. In the present study, we analysed some parallelisms between central and enteric nervous system (ENS) in humans based on ultrastructural and immunohistochemical techniques. Thus, we described the presence of primary cilia in some subtypes of glial cells and Interstitial Cells of Cajal (ICCs) and we performed 3-D reconstructions to better characterise their features. Besides, we studied the expression of several adult neurogenesis-related proteins. Immature neuron markers were found in human ENS, supporting the existence of adult neurogenesis. However, only ICCs showed proliferation markers. Hence, we propose a new paradigm where ICCs would constitute the original neural stem cells which, through asymmetrical cell division, would generate the new-born neurons.

Stromal cells of giant cell tumor of bone show primary cilia in giant cell tumor of bone.

Giant cell tumor of bone (GCTB) is a locally aggressive primary bone neoplasm composed by tumoral stromal cells (SCs) and a reactive component that consists of monocytic/histiocytic cells that give rise by fusion to osteoclast-like multinucleated cells. Recently, specific Histone 3.3 mutations have been demonstrated in SCs of GCTB. Many of the pathways related to bone proliferation and regulation depend on the primary cilium, a microtubule-based organelle that protrudes outside the cell and acts as a sensorial antenna. In the present work, we aimed to study the presence and role of primary cilia in GCTB. Ultrastructural, immunohistochemical, and immunofluorescence studies were performed in order to demonstrate, for the first time, that the primary cilium is located in spindle-shaped SCs of GCTB. Moreover, we showed Hedgehog (Hh) signaling pathway activation in these cells. Hence, primary cilia may play a relevant role in GCTB tumorogenesis through Hh signaling activation in SCs. RESEARCH HIGHLIGHTS: Transmission electron microscopy allows describing and differentiating cellular subpopulations in giant cell tumor of bone (GCTB). The primary cilium is present in some tumoral stromal cells of GCTB. Hedgehog signalling is activated in these cells.

Description of Two Families with New Mutations in Familial Cerebral Cavernous Malformations Genes.

Cerebral cavernous malformations (CCMs) are dilated aberrant leaky capillaries located in the Central Nervous System. Familial CCM is an autosomal dominant inherited disorder related to mutations in KRIT1, Malcavernin or PDCD10. We show two unrelated families presenting familial CCM due to two new mutations in KRIT1 and PDCD10, producing truncated proteins. Clinical phenotype was highly variable among patients from asymptomatic individuals to diplopia, seizures or severe intracranial hemorrhage. PDCD10 patients usually show a more aggressive course and they frequently showed multiple meningiomas. This work provides evidence for the pathogenicity of two new mutations in CCM genes and supports previous findings regarding familial CCM and multiple meningiomas.

Autoimmune GFAP astrocytopathy presenting with remarkable CNS hyperexcitability and oculogyric crises.

The autoimmune GFAP astrocytopathy has been associated with meningoencephalomyelitis that usually responds to glucocorticoids. We report a 20-year-old man that developed an acute and severe meningoencephalomyelitis with remarkable CNS hyperexcitability and oculogyric crises. CSF analysis showed hypoglycorrhachia, pleocytosis, elevated ADA, and CSF-immunofluorescence characteristic of autoimmune GFAP astrocytopathy. MRI showed lesions at thalamus, corpus-callosum, dorsal pons and dentate nucleus with associated myelitis. Immunotherapy led to a full recovery, although MRI activity was observed at follow-up. CNS hyperexcitability, typically seen in other immune-mediated syndromes, represents a novel presenting form to be included as part of the clinical spectrum of this entity.

Management of an outbreak of botulism with benign clinical presentation.

Botulism is a life-threatening presynaptic disorder of the neuromuscular transmission produced by the neurotoxin elaborated by the botulinum neurotoxin-producing clostridia. We describe the management of a case series of 14 patients, members of 5 different families that were exposed to home-canned tuna and developed symptoms compatible with a mild clinical presentation of foodborne botulism. The electrophysiological study of the index case represented a reliable diagnostic test as it demonstrated a slight presynaptic dysfunction of the neuromuscular junction. Definite diagnosis was later confirmed by microbiological tests. Out of 14, only 3 patients presenting with a shorter period from symptom onset and with signs of multiple cranial neuropathies received botulinum antitoxin. All the patients remained stable and recovered progressively. Treatment with antitoxin may not be necessary in patients with late-presenting disease and mild and stable clinical picture.

Primary cilia presence and implications in bladder cancer progression and invasiveness.

Urothelial bladder cancer is the tenth most common cancer worldwide. It is divided into muscle and non-muscle invading bladder cancer. Primary cilia have been related to several cancer hallmarks such as proliferation, epithelial-to-mesenchymal transition (EMT) or tumoral progression mainly through signaling pathways as Hedgehog (Hh). In the present study, we used immunohistochemical and ultrastructural techniques in human tissues of healthy bladder, non-muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC) to study and clarify the activation of epithelial-to-mesenchymal transition and Hedgehog signaling pathway and the presence of primary cilia. Thus, we found a clear correlation between EMT and Hedgehog activation and bladder cancer stage and progression. Moreover, we identified the presence of primary cilia in these tissues. Interestingly, we found that in NMIBC, some ciliated cells cross the basement membrane and localized in lamina propria, near blood vessels. These results show a correlation between EMT beginning from urothelial basal cells and primary cilia assembly and suggest a potential implication of this structure in tumoral migration and invasiveness (likely in a Hh-dependent way). Hence, primary cilia may play a fundamental role in urothelial bladder cancer progression and suppose a potential therapeutic target.

Hedgehog signalling pathway activation in gastrointestinal stromal tumours is mediated by primary cilia.

BACKGROUND: Gastrointestinal stromal tumour (GIST) is a mesenchymal cancer which derives from interstitial cells of Cajal. To determine whether a relationship between Hedgehog (Hh) signalling pathway and primary cilia exists in GIST tumours is intended here. METHODS: Immunohistochemical, immunofluorescence and ultrastructural techniques were performed in this study. RESULTS: We show that GIST cells present primary cilia (an antenna-like structure based on microtubules). But, moreover, we prove Hedgehog signalling pathway activation in these tumours (a pathway related with tumoural features such as proliferation, migration or stemness) and we show for the first time that this signalling pathway activation in GIST is mediated by primary cilia, likely in a paracrine way. CONCLUSION: Thus, primary cilia and Hedgehog signalling would be fundamental in tumoural microenvironment control of GIST cells for their maintenance, differentiation and proliferation.

Ultrastructural and immunohistochemical study of phenotypic switch in gastrointestinal smooth muscle cells.

Dedifferentiation is a loss of phenotypic specialization that converts differentiated cells into adult stem cells in order to proliferate and differentiate into replacement tissue. This occurs in several tissues from various organs, such as smooth muscle cells (SMCs) of the mammalian gastrointestinal tract. The aim of this study was to describe ultrastructural and immunohistochemical changes in SMCs which could be compatible with a dedifferentiation process in human and rabbit intestinal muscles. Ultrastructural study and immunohistochemical staining (SMemb and MyoD) on human and rabbit duodenum tissue sections were performed. In both species, this dedifferentiation process is characterized by a loss of intercellular junctions, increased intercellular spaces, cytoskeletal disorganization, perinuclear accumulation of large vacuoles that tend to fuse, rupture of the vacuole membrane and release of cytoplasmic fragments. Dedifferentiated cells show the characteristic phenotype of a mesenchymal cell with scarce perinuclear cytoplasm, long cytoplasmic prolongations and finely distributed granular chromatin in the nucleus. These morphological changes are accompanied by a modulation to a less mature phenotype showing immunoreactivity for the embryonic form of the myosin heavy chain and for the myogenic regulatory factor MyoD. We suggest that SMC dedifferentiation includes the elimination of the contractile apparatus, the activation of the nucleus and the re-expression of embryonic markers. We described an ultrastructural dedifferentiation process possible in intestinal SMCs. This dedifferentiation process seems to play a key role in the homeostasis of the intestinal muscle.