Guanylate Kinase 1 Deficiency: A Novel and Potentially Treatable Mitochondrial DNA Depletion/Deletions Disease.

OBJECTIVE: Mitochondrial DNA (mtDNA) depletion/deletions syndrome (MDDS) comprises a group of diseases caused by primary autosomal defects of mtDNA maintenance. Our objective was to study the etiology of MDDS in 4 patients who lack pathogenic variants in known genetic causes. METHODS: Whole exome sequencing of the probands was performed to identify pathogenic variants. We validated the mitochondrial defect by analyzing mtDNA, mitochondrial dNTP pools, respiratory chain activities, and GUK1 activity. To confirm pathogenicity of GUK1 deficiency, we expressed 2 GUK1 isoforms in patient cells. RESULTS: We identified biallelic GUK1 pathogenic variants in all 4 probands who presented with ptosis, ophthalmoparesis, and myopathic proximal limb weakness, as well as variable hepatopathy and altered T-lymphocyte profiles. Muscle biopsies from all probands showed mtDNA depletion, deletions, or both, as well as reduced activities of mitochondrial respiratory chain enzymes. GUK1 encodes guanylate kinase, originally identified as a cytosolic enzyme. Long and short isoforms of GUK1 exist. We observed that the long isoform is intramitochondrial and the short is cytosolic. In probands' fibroblasts, we noted decreased GUK1 activity causing unbalanced mitochondrial dNTP pools and mtDNA depletion in both replicating and quiescent fibroblasts indicating that GUK1 deficiency impairs de novo and salvage nucleotide pathways. Proband fibroblasts treated with deoxyguanosine and/or forodesine, a purine phosphatase inhibitor, ameliorated mtDNA depletion, indicating potential pharmacological therapies. INTERPRETATION: Primary GUK1 deficiency is a new and potentially treatable cause of MDDS. The cytosolic isoform of GUK1 may contribute to the T-lymphocyte abnormality, which has not been observed in other MDDS disorders. ANN NEUROL 2024.

Unleashing the potential of mRNA therapeutics for inherited neurological diseases.

Neurological monogenic loss-of-function diseases are hereditary disorders resulting from gene mutations that decrease or abolish the normal function of the encoded protein. These conditions pose significant therapeutic challenges, which may be resolved through the development of innovative therapeutic strategies. RNA-based technologies, such as mRNA replacement therapy, have emerged as promising and increasingly viable treatments. Notably, mRNA therapy exhibits significant potential as a mutation-agnostic approach that can address virtually any monogenic loss-of-function disease. Therapeutic mRNA carries the information for a healthy copy of the defective protein, bypassing the problem of targeting specific genetic variants. Moreover, unlike conventional gene therapy, mRNA-based drugs are delivered through a simplified process that requires only transfer to the cytoplasm, thereby reducing the mutagenic risks related to DNA integration. Additionally, mRNA therapy exerts a transient effect on target cells, minimizing the risk of long-term unintended consequences. The remarkable success of mRNA technology for developing coronavirus disease 2019 vaccines has rekindled interest in mRNA as a cost-effective method for delivering therapeutic proteins. However, further optimization is required to enhance mRNA delivery, particularly to the CNS, while minimizing adverse drug reactions and toxicity. In this comprehensive review, we delve into past, present and ongoing applications of mRNA therapy for neurological monogenic loss-of-function diseases. We also discuss the promises and potential challenges presented by mRNA therapeutics in this rapidly advancing field. Ultimately, we underscore the full potential of mRNA therapy as a game-changing therapeutic approach for neurological disorders.

Six-minute walk test as outcome measure of fatigability in adults with spinal muscular atrophy treated with nusinersen.

INTRODUCTION/AIMS: Fatigue (subjective perception) and fatigability (objective motor performance worsening) are relevant aspects of disability in individuals with spinal muscular atrophy (SMA). The effect of nusinersen on fatigability in SMA patients has been investigated with conflicting results. We aimed to evaluate this in adult with SMA3. METHODS: We conducted a multicenter retrospective cohort study, including adult ambulant patients with SMA3, data available on 6-minute walk test (6MWT) and Hammersmith Functional Motor Scale-Expanded (HFMSE) at baseline and at least at 6 months of treatment with nusinersen. We investigated fatigability, estimated as 10% or higher decrease in walked distance between the first and sixth minute of the 6MWT, at baseline and over the 14-month follow-up. RESULTS: Forty-eight patients (56% females) were included. The 6MWT improved after 6, 10, and 14 months of treatment (p < 0.05). Of the 27 patients who completed the entire follow-up, 37% improved (6MWT distance increase ≥30 m), 48.2% remained stable, and 14.8% worsened (6MWT distance decline ≥30 m). Fatigability was found at baseline in 26/38 (68%) patients and confirmed at subsequent time points (p < 0.05) without any significant change over the treatment period. There was no correlation between fatigability and SMN2 copy number, sex, age at disease onset, age at baseline, nor with 6MWT total distance and baseline HFMSE score. DISCUSSION: Fatigability was detected at baseline in approximately 2/3 of SMA3 walker patients, without any correlation with clinical features, included motor performance. No effect on fatigability was observed during the 14-month treatment period with nusinersen.

Regional spreading pattern is associated with clinical phenotype in amyotrophic lateral sclerosis.

Increasing evidence shows that disease spreading in amyotrophic lateral sclerosis (ALS) follows a preferential pattern with more frequent involvement of contiguous regions from the site of symptom onset. The aim of our study was to assess if: (i) the burden of upper (UMN) and lower motor neuron (LMN) involvement influences directionality of disease spreading; (ii) specific patterns of disease progression are associated with motor and neuropsychological features of different ALS subtypes (classic, bulbar, primary lateral sclerosis, UMN-predominant, progressive muscular atrophy, flail arm, flail leg); and (iii) specific clinical features may help identify ALS subtypes, which remain localized to the site of onset for a prolonged time (regionally entrenching ALS). A single-centre, retrospective cohort of 913 Italian ALS patients was evaluated to assess correlations between directionality of the disease process after symptom onset and motor/neuropsychological phenotype. All patients underwent an extensive evaluation including the following clinical scales: Penn Upper Motor Neuron Score (PUMNS), MRC Scale for Muscle Strength and the Edinburgh Cognitive and Behavioural ALS Screen (ECAS). The most frequent initial spreading pattern was that towards adjacent horizontal regions (77.3%), which occurred preferentially in patients with lower MRC scores (P = 0.038), while vertical diffusion (21.1%) was associated with higher PUMNS (P < 0.001) and with reduced survival (P < 0.001). Non-contiguous disease spreading was associated with more severe UMN impairment (P = 0.003), while contiguous disease pattern with lower MRC scores. Furthermore, non-contiguous disease spreading was associated with more severe cognitive impairment in both executive and visuospatial ECAS domains. Individuals with regionally entrenching ALS were more frequently female (45.6% versus 36.9%; P = 0.028) and had higher frequencies of symmetric disease onset (40.3% versus 19.7%; P < 0.001) and bulbar phenotype (38.5% versus 16.4%; P < 0.001). Our study suggests that motor phenotypes characterized by a predominant UMN involvement are associated with a vertical pattern of disease progression reflecting ipsilateral spreading within the motor cortex, while those with predominant LMN involvement display more frequently a horizontal spreading from one side of the spinal cord to the other. These observations raise the hypothesis that one of the mechanisms underlying disease spreading in ALS pathology is represented by diffusion of toxic factors in the neuron microenvironment. Finally, it is possible that in our cohort, regionally entrenching ALS forms are mainly observed in patients with atypical bulbar phenotypes, characterized by a slowly progressive course and relatively benign prognosis.

Multi-omics profiling of CSF from spinal muscular atrophy type 3 patients after nusinersen treatment: a 2-year follow-up multicenter retrospective study.

Spinal muscular atrophy (SMA) is a neurodegenerative disorder caused by mutations in the SMN1 gene resulting in reduced levels of the SMN protein. Nusinersen, the first antisense oligonucleotide (ASO) approved for SMA treatment, binds to the SMN2 gene, paralogue to SMN1, and mediates the translation of a functional SMN protein. Here, we used longitudinal high-resolution mass spectrometry (MS) to assess both global proteome and metabolome in cerebrospinal fluid (CSF) from ten SMA type 3 patients, with the aim of identifying novel readouts of pharmacodynamic/response to treatment and predictive markers of treatment response. Patients had a median age of 33.5 [29.5; 38.25] years, and 80% of them were ambulant at time of the enrolment, with a median HFMSE score of 37.5 [25.75; 50.75]. Untargeted CSF proteome and metabolome were measured using high-resolution MS (nLC-HRMS) on CSF samples obtained before treatment (T0) and after 2 years of follow-up (T22). A total of 26 proteins were found to be differentially expressed between T0 and T22 upon VSN normalization and LIMMA differential analysis, accounting for paired replica. Notably, key markers of the insulin-growth factor signaling pathway were upregulated after treatment together with selective modulation of key transcription regulators. Using CombiROC multimarker signature analysis, we suggest that detecting a reduction of SEMA6A and an increase of COL1A2 and GRIA4 might reflect therapeutic efficacy of nusinersen. Longitudinal metabolome profiling, analyzed with paired t-Test, showed a significant shift for some aminoacid utilization induced by treatment, whereas other metabolites were largely unchanged. Together, these data suggest perturbation upon nusinersen treatment still sustained after 22 months of follow-up and confirm the utility of CSF multi-omic profiling as pharmacodynamic biomarker for SMA type 3. Nonetheless, validation studies are needed to confirm this evidence in a larger sample size and to further dissect combined markers of response to treatment.

Ischemic optic neuropathy as first presentation in patient with m.3243 A > G MELAS classic mutation.

BACKGROUND: Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is a systemic disorder in which multi-organ dysfunction may occur from mitochondrial metabolism failure. Maternally inherited mutations in the MT-TL1 gene are the most frequent causes for this disorder. Clinical manifestations may include stroke-like episodes, epilepsy, dementia, headache and myopathy. Among these, acute visual failure, usually in association with cortical blindness, can occur because of stroke-like episodes affecting the occipital cortex or the visual pathways. Vision loss due to optic neuropathy is otherwise considered a typical manifestation of other mitochondrial diseases such as Leber hereditary optic neuropathy (LHON). CASE PRESENTATION: Here we describe a 55-year-old woman, sister of a previously described patient with MELAS harbouring the m.3243A > G (p.0, MT-TL1) mutation, with otherwise unremarkable medical history, that presented with subacute, painful visual impairment of one eye, accompanied by proximal muscular pain and headache. Over the next weeks, she developed severe and progressive vision loss limited to one eye. Ocular examination confirmed unilateral swelling of the optic nerve head; fluorescein angiography showed segmental perfusion delay in the optic disc and papillary leakage. Neuroimaging, blood and CSF examination and temporal artery biopsy ruled out neuroinflammatory disorders and giant cell arteritis (GCA). Mitochondrial sequencing analysis confirmed the m.3243A > G transition, and excluded the three most common LHON mutations, as well as the m.3376G > A LHON/MELAS overlap syndrome mutation. Based on the constellation of clinical symptoms and signs presented in our patient, including the muscular involvement, and the results of the investigations, the diagnosis of optic neuropathy as a stroke-like event affecting the optic disc was performed. L-arginine and ubidecarenone therapies were started with the aim to improve stroke-like episode symptoms and prevention. The visual defect remained stable with no further progression or outbreak of new symptoms. CONCLUSIONS: Atypical clinical presentations must be always considered in mitochondrial disorders, even in well-described phenotypes and when mutational load in peripheral tissue is low. Mitotic segregation of mitochondrial DNA (mtDNA) does not allow to know the exact degree of heteroplasmy existent within different tissue, such as retina and optic nerve. Important therapeutic implications arise from a correct diagnosis of atypical presentation of mitochondrial disorders.

Insights into the identification of a molecular signature for amyotrophic lateral sclerosis exploiting integrated microRNA profiling of iPSC-derived motor neurons and exosomes.

Amyotrophic lateral sclerosis (ALS) is a rare neurodegenerative disorder characterized by progressive degeneration of motor neurons (MNs). Most cases are sporadic, whereas 10% are familial. The pathological mechanisms underlying the disease are partially understood, but it is increasingly being recognized that alterations in RNA metabolism and deregulation of microRNA (miRNA) expression occur in ALS. In this study, we performed miRNA expression profile analysis of iPSC-derived MNs and related exosomes from familial patients and healthy subjects. We identified dysregulation of miR-34a, miR-335 and miR-625-3p expression in both MNs and exosomes. These miRNAs regulate genes and pathways which correlate with disease pathogenesis, suggesting that studying miRNAs deregulation can contribute to deeply investigate the molecular mechanisms underlying the disease. We also assayed the expression profile of these miRNAs in the cerebrospinal fluid (CSF) of familial (fALS) and sporadic patients (sALS) and we identified a significant dysregulation of miR-34a-3p and miR-625-3p levels in ALS compared to controls. Taken together, all these findings suggest that miRNA analysis simultaneously performed in different human biological samples could represent a promising molecular tool to understand the etiopathogenesis of ALS and to develop new potential miRNA-based strategies in this new propitious therapeutic era.

Advancing Stroke Research on Cerebral Thrombi with Omic Technologies.

Cerebrovascular diseases represent a leading cause of disability, morbidity, and death worldwide. In the last decade, the advances in endovascular procedures have not only improved acute ischemic stroke care but also conceded a thorough analysis of patients' thrombi. Although early anatomopathological and immunohistochemical analyses have provided valuable insights into thrombus composition and its correlation with radiological features, response to reperfusion therapies, and stroke etiology, these results have been inconclusive so far. Recent studies applied single- or multi-omic approaches-such as proteomics, metabolomics, transcriptomics, or a combination of these-to investigate clot composition and stroke mechanisms, showing high predictive power. Particularly, one pilot studies showed that combined deep phenotyping of stroke thrombi may be superior to classic clinical predictors in defining stroke mechanisms. Small sample sizes, varying methodologies, and lack of adjustments for potential confounders still represent roadblocks to generalizing these findings. However, these techniques hold the potential to better investigate stroke-related thrombogenesis and select secondary prevention strategies, and to prompt the discovery of novel biomarkers and therapeutic targets. In this review, we summarize the most recent findings, overview current strengths and limitations, and present future perspectives in the field.

Adults with spinal muscular atrophy: a large-scale natural history study shows gender effect on disease.

BACKGROUND: Natural history of spinal muscular atrophy (SMA) in adult age has not been fully elucidated yet, including factors predicting disease progression and response to treatments. Aim of this retrospective, cross-sectional study, is to investigate motor function across different ages, disease patterns and gender in adult SMA untreated patients. METHODS: Inclusion criteria were as follows: (1) clinical and molecular diagnosis of SMA2, SMA3 or SMA4 and (2) clinical assessments performed in adult age (>18 years). RESULTS: We included 64 (38.8%) females and 101 (61.2%) males (p=0.0025), among which 21 (12.7%) SMA2, 141 (85.5%) SMA3 and 3 (1.8%) SMA4. Ratio of sitters/walkers within the SMA3 subgroup was significantly (p=0.016) higher in males (46/38) than in females (19/38). Median age at onset was significantly (p=0.0071) earlier in females (3 years; range 0-16) than in males (4 years; range 0.3-28), especially in patients carrying 4 SMN2 copies. Median Hammersmith Functional Rating Scale Expanded scores were significantly (p=0.0040) lower in males (16, range 0-64) than in females (40, range 0-62); median revised upper limb module scores were not significantly (p=0.059) different between males (24, 0-38) and females (33, range 0-38), although a trend towards worse performance in males was observed. In SMA3 patients carrying three or four SMN2 copies, an effect of female sex in prolonging ambulation was statistically significant (p=0.034). CONCLUSIONS: Our data showed a relevant gender effect on SMA motor function with higher disease severity in males especially in the young adult age and in SMA3 patients.

Diagnostic and prognostic value of CSF neurofilaments in a cohort of patients with motor neuron disease: A cross-sectional study.

Motor neuron disease (MND) is a rare group of disorders characterized by degeneration of motor neurons (MNs). The most common form of MND, amyotrophic lateral sclerosis (ALS), is an incurable disease with a variable rate of progression. The search of robust biomarkers able to discriminate among different ALS forms is paramount to properly stratify patients, and to identify those who could most likely benefit from experimental therapies. Phosphorylated-neurofilament heavy chain (p-NfH) and neurofilament light chain (NfL) are neuron-specific components of the cytoskeleton and may represent reliable markers of neuronal injury in neurological disorders. In this study, we described our cohort of ALS patients in order to investigate whether and how cerebrospinal fluid (CSF) p-NfH and NfL levels may reflect progression rate, MN involvement and the extent of neurodegeneration. CSF p-NfH and NfL were significantly increased in ALS compared with healthy and disease controls, including patients with other forms of MND, and were higher in patients with more aggressive disease course, reflecting progression rate. We also evaluated neurofilament diagnostic accuracy in our centre, identifying with high sensitivity and 100% specificity cut-off values of 0.652 ng/mL for CSF p-NfH (P < .0001) and of 1261 pg/mL for NfL (P < .0001) in discriminating ALS from healthy controls. CSF neurofilaments were significantly correlated with ALS progression rate. Overall, CSF neurofilaments appear to reflect the burden of neurodegeneration in MND and represent reliable diagnostic and prognostic biomarkers in ALS.

Impact of COVID-19 on the quality of life of patients with neuromuscular disorders in the Lombardy area, Italy.

INTRODUCTION: /AIMS: Patients with neuromuscular disorders (NMDs), including many elderly, immunosuppressed, and disabled individuals, may have been particularly affected during the coronavirus disease 2019 (COVID-19) pandemic in Lombardy, a COVID-19 high-incidence area between February and May 2020. We aimed to evaluate the effects of the COVID-19 pandemic on the quality of life (QoL) and perceived disease burden of this group of patients. METHODS: We conducted a cross-sectional phone-based survey study between June 1 and June 14, 2020, on a sample of 240 NMD patients followed at our clinic in Milan, Italy. We asked about perceived NMD burden and QoL before and during the COVID-19 pandemic. We collected responses on access to outpatient care and ancillary services. We investigated the presence of symptoms suggestive of COVID-19 infection and confirmed cases. RESULTS: We collected 205 responses: 53 patients (25.9%) reported a subjective worsening of the underlying NMD. QoL measures showed a significant worsening between pre and pandemic time frames (odds ratio, 2.14 95%; confidence interval, 1.82-2.51). Outpatient visits were postponed in more than half of cases (57.1%), with 104 patients (50.7%) experiencing a cancellation of scheduled diagnostic tests. 79 patients (38.5%) reported at least one symptom attributable to COVID-19 infection. Among the 10 patients tested with nasopharyngeal swabs, 6 tested positive and 3 died from respiratory failure, including 2 patients on corticosteroid/ immunosuppressive therapy. DISCUSSION: The COVID-19 pandemic affected QoL and limited access to outpatient care and ancillary services of NMD patients in Lombardy between February and May 2020.

Nusinersen treatment and cerebrospinal fluid neurofilaments: An explorative study on Spinal Muscular Atrophy type 3 patients.

The antisense oligonucleotide Nusinersen has been recently licensed to treat spinal muscular atrophy (SMA). Since SMA type 3 is characterized by variable phenotype and milder progression, biomarkers of early treatment response are urgently needed. We investigated the cerebrospinal fluid (CSF) concentration of neurofilaments in SMA type 3 patients treated with Nusinersen as a potential biomarker of treatment efficacy. The concentration of phosphorylated neurofilaments heavy chain (pNfH) and light chain (NfL) in the CSF of SMA type 3 patients was evaluated before and after six months since the first Nusinersen administration, performed with commercially available enzyme-linked immunosorbent assay (ELISA) kits. Clinical evaluation of SMA patients was performed with standardized motor function scales. Baseline neurofilament levels in patients were comparable to controls, but significantly decreased after six months of treatment, while motor functions were only marginally ameliorated. No significant correlation was observed between the change in motor functions and that of neurofilaments over time. The reduction of neurofilament levels suggests a possible early biochemical effect of treatment on axonal degeneration, which may precede changes in motor performance. Our study mandates further investigations to assess neurofilaments as a marker of treatment response.

Nusinersen safety and effects on motor function in adult spinal muscular atrophy type 2 and 3.

OBJECTIVE: To retrospectively investigate safety and efficacy of nusinersen in a large cohort of adult Italian patients with spinal muscular atrophy (SMA). METHODS: Inclusion criteria were: (1) clinical and molecular diagnosis of SMA2 or SMA3; (2) nusinersen treatment started in adult age (>18 years); (3) clinical data available at least at baseline (T0-beginning of treatment) and 6 months (T6). RESULTS: We included 116 patients (13 SMA2 and 103 SMA3) with median age at first administration of 34 years (range 18-72). The Hammersmith Functional Rating Scale Expanded (HFMSE) in patients with SMA3 increased significantly from baseline to T6 (median change +1 point, p<0.0001), T10 (+2, p<0.0001) and T14 (+3, p<0.0001). HFMSE changes were independently significant in SMA3 sitter and walker subgroups. The Revised Upper Limb Module (RULM) in SMA3 significantly improved between T0 and T14 (median +0.5, p=0.012), with most of the benefit observed in sitters (+2, p=0.018). Conversely, patients with SMA2 had no significant changes of median HFMSE and RULM between T0 and the following time points, although a trend for improvement of RULM was observed in those with some residual baseline function. The rate of patients showing clinically meaningful improvements (as defined during clinical trials) increased from 53% to 69% from T6 to T14. CONCLUSIONS: Our data provide further evidence of nusinersen safety and efficacy in adult SMA2 and SMA3, with the latter appearing to be cumulative over time. In patients with extremely advanced disease, effects on residual motor function are less clear.

Herpes Simplex virus type 2 myeloradiculitis with a pure motor presentation in a liver transplant recipient.

In this case report, we describe the first PCR-confirmed case of HSV2 myeloradiculitis with a purely motor presentation, occurring in a 68-year-old liver transplant recipient. The patient reported ascending weakness with no sensory nor sphincteric symptoms, thereby resembling acute demyelinating inflammatory neuropathy, or Guillain-Barré syndrome. HSV2 was detected in cerebrospinal fluid by PCR, and the patient was successfully treated with intravenous Acyclovir.

Diagnostic and Prognostic Role of Blood and Cerebrospinal Fluid and Blood Neurofilaments in Amyotrophic Lateral Sclerosis: A Review of the Literature.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder affecting upper and lower motor neurons (MNs) that still lacks an efficacious therapy. The failure of recent therapeutic trials in ALS, other than depending on the poor knowledge of pathogenic mechanisms responsible for MNs loss, is largely due to diagnostic delay and the lack of reliable biomarkers for diagnosis, prognosis and response to pharmacologic intervention. Neurofilaments (Nfs) are neuron-specific cytoskeletal proteins, whose levels increased in biological fluids proportionally to the degree of axonal damage, both in normal and in pathologic conditions, representing potential biomarkers in various neurological disorders, such as motor neuron disorder (MND). Growing evidence has shown that phosphorylated neurofilaments heavy chain (p-NfH) and neurofilaments light chain (NfL) are increased in blood and cerebrospinal fluid (CSF) of ALS patients compared to healthy and neurological controls and are found to correlate with disease progression. In this review, we reported the most relevant studies investigating the diagnostic and prognostic role of Nfs in ALS. Given their reliability and reproducibility, we consider Nfs as promising and useful biomarkers in diagnosis of MND, early patient identification for inclusion in clinical trials, prediction of disease progression, and response to pharmacological intervention, and we suggest the validation of their measurement in clinical activity.

Exploiting the role of CSF NfL, CHIT1, and miR-181b as potential diagnostic and prognostic biomarkers for ALS.

Amyotrophic lateral sclerosis (ALS) is a rare neurodegenerative disorder characterized by relentless and progressive loss of motor neurons. A molecular diagnosis, supported by the identification of specific biomarkers, might promote the definition of multiple biological subtypes of ALS, improving patient stratification and providing prognostic information. Here, we investigated the levels of neurofilament light chain (NfL), chitotriosidase (CHIT1) and microRNA-181b (miR-181b) in the cerebrospinal fluid (CSF) of ALS subjects (N = 210) as well as neurologically healthy and neurological disease controls (N = 218, including N = 74 with other neurodegenerative diseases) from a large European multicentric cohort, evaluating their specific or combined utility as diagnostic and prognostic biomarkers. NfL, CHIT1 and miR-181b all showed significantly higher levels in ALS subjects compared to controls, with NfL showing the most effective diagnostic performance. Importantly, all three biomarkers were increased compared to neurodegenerative disease controls and, specifically, to patients with Alzheimer's disease (AD; N = 44), with NfL and CHIT1 being also higher in ALS than in alpha-synucleinopathies (N = 22). Notably, ALS patients displayed increased CHIT1 levels despite having, compared to controls, a higher prevalence of a polymorphism lowering CHIT1 expression. While no relationship was found between CSF miR-181b and clinical measures in ALS (disease duration, functional disability, and disease progression rate), CSF NfL was the best independent predictor of disease progression and survival. This study deepens our knowledge of ALS biomarkers, highlighting the relative specificity of CHIT1 for ALS among neurodegenerative diseases and appraising the potential diagnostic utility of CSF miR-181b.

Shaping the Neurovascular Unit Exploiting Human Brain Organoids.

Brain organoids, three-dimensional cell structures derived from pluripotent stem cells, closely mimic key aspects of the human brain in vitro, providing a powerful tool for studying neurodevelopment and disease. The neuroectodermal induction protocol employed for brain organoid generation primarily gives rise to the neural cellular component but lacks the vital vascular system, which is crucial for the brain functions by regulating differentiation, migration, and circuit formation, as well as delivering oxygen and nutrients. Many neurological diseases are caused by dysfunctions of cerebral microcirculation, making vascularization of human brain organoids an important tool for pathogenetic and translational research. Experimentally, the creation of vascularized brain organoids has primarily focused on the fusion of vascular and brain organoids, on organoid transplantation in vivo, and on the use of microfluidic devices to replicate the intricate microenvironment of the human brain in vitro. This review summarizes these efforts and highlights the importance of studying the neurovascular unit in a forward-looking perspective of leveraging their use for understanding and treating neurological disorders.

Investigating the prevalence of MFN2 mutations in amyotrophic lateral sclerosis: insights from an Italian cohort.

The MFN2 gene encodes mitofusin 2, a key protein for mitochondrial fusion, transport, maintenance and cell communication. MFN2 mutations are primarily linked to Charcot-Marie-Tooth disease type 2A. However, a few cases of amyotrophic lateral sclerosis and amyotrophic lateral sclerosis/frontotemporal dementia phenotypes with concomitant MFN2 mutations have been previously reported. This study examines the clinical and genetic characteristics of an Italian cohort of amyotrophic lateral sclerosis patients with rare, non-synonymous MFN2 mutations. A group of patients (n = 385) diagnosed with amyotrophic lateral sclerosis at our Neurology Units between 2008 and 2023 underwent comprehensive molecular testing, including MFN2. After excluding pathogenic mutations in the main amyotrophic lateral sclerosis-related genes (i.e. C9orf72, SOD1, FUS and TARDBP), MFN2 variants were classified based on the American College of Medical Genetics and Genomics guidelines, and demographic and clinical data of MFN2-mutated patients were retrieved. We identified 12 rare, heterozygous, non-synonymous MFN2 variants in 19 individuals (4.9%). Eight of these variants, carried by nine patients (2.3%), were either pathogenic, likely pathogenic or variants of unknown significance according to the American College of Medical Genetics and Genomics guidelines. Among these patients, four exhibited a familial pattern of inheritance. The observed phenotypes included classic and bulbar amyotrophic lateral sclerosis, amyotrophic lateral sclerosis/frontotemporal dementia, flail arm, flail leg and progressive muscular atrophy. Median survival after disease onset was extremely variable, ranging from less than 1 to 13 years. This study investigates the prevalence of rare, non-synonymous MFN2 variants within an Italian cohort of amyotrophic lateral sclerosis patients, who have been extensively investigated, enhancing our knowledge of the underlying phenotypic spectrum. Further research is needed to understand whether MFN2 mutations contribute to motor neuron disease and to what extent. Improving our knowledge regarding the genetic basis of amyotrophic lateral sclerosis is crucial both in a diagnostic and therapeutic perspective.

Unraveling the Neurological Complexity of Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal Protein, and Skin Changes Syndrome: A Report of a Challenging Case of a Young Woman and Cutting-Edge Advancements in the Field.

POEMS syndrome-characterized by polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes-is an uncommon and complex paraneoplastic disorder encompassing a diverse array of symptoms. Here we report the challenging case of a 34-year-old female who sought medical attention at the emergency department due to distal lower limb weakness. She was breastfeeding her first child at that time. Her condition rapidly deteriorated, making it difficult for her to perform simple tasks independently. Initially, she struggled with activities like jumping or climbing stairs. Eventually, her ability to walk was also compromised. These symptoms underscored the swift evolution of her polyneuropathy. Nerve conduction studies and electromyography confirmed a diagnosis of mixed demyelinating and axonal polyneuropathy. Subsequent investigations, including bone marrow biopsy and immunochemistry testing, revealed a plasma cell disorder characterized by lambda monoclonal gammopathy, along with elevated levels of vascular endothelial growth factor (VEGF > 8000 pg/mL). This pivotal finding led to the diagnosis of POEMS syndrome, prompting the initiation of antineoplastic therapy (daratumumab-lenalidomide-dexamethasone) to manage this condition. An autologous cell transplantation was planned. The rarity of POEMS syndrome and its diverse clinical manifestations often lead to an incorrect or delayed diagnosis. Our case underscores the importance of considering this syndrome in patients presenting with acute or subacute polyneuropathy, even if the patients are young. In conclusion, this case elucidates the diagnostic complexities of POEMS syndrome, emphasizing the integral role of comprehensive multidisciplinary evaluations and the potential influence of increased VEGF as a diagnostic key element and possible therapeutic target.

Identification of Novel Biomarkers of Spinal Muscular Atrophy and Therapeutic Response by Proteomic and Metabolomic Profiling of Human Biological Fluid Samples.

Spinal muscular atrophy (SMA) is a neuromuscular disease resulting from mutations or deletions in SMN1 that lead to progressive death of alpha motor neurons, ultimately leading to severe muscle weakness and atrophy, as well as premature death in the absence of treatment. Recent approval of SMN-increasing medications as SMA therapy has altered the natural course of the disease. Thus, accurate biomarkers are needed to predict SMA severity, prognosis, drug response, and overall treatment efficacy. This article reviews novel non-targeted omics strategies that could become useful clinical tools for patients with SMA. Proteomics and metabolomics can provide insights into molecular events underlying disease progression and treatment response. High-throughput omics data have shown that untreated SMA patients have different profiles than controls. In addition, patients who clinically improved after treatment have a different profile than those who did not. These results provide a glimpse on potential markers that could assist in identifying therapy responders, in tracing the course of the disease, and in predicting its outcome. These studies have been restricted by the limited number of patients, but the approaches are feasible and can unravel severity-specific neuro-proteomic and metabolic SMA signatures.