BACKGROUND AND AIMS:Hereditary transthyretin amyloidosis (ATTRv) is a multisystemic disease where early neuropathy signs are challenging to detect conventionally. This study aimed to evaluate hand motor performance in ATTRv using the Hand Test System (HTS) across disease stages and examine correlations with standard measures. METHODS:A total of 113 individuals were enrolled: 74 patients with ATTRv (divided according to Familial Amyloid Polyneuropathy [FAP] stage into FAP0: pre-symptomatic with confirmed TTR mutations, n = 16; FAP1: mild sensory/motor symptoms, n = 40; FAP2: ambulatory with assistance, n = 18) and 39 healthy controls. All participants underwent HTS evaluation; 9-Hole Peg Test (9HPT); handgrip and tripod pinch strength testing; Thumb Opposition Test (TOT); Neuropathy Impairment Score (NIS); Disabilities of the Arm, Shoulder and Hand questionnaire (DASH); and Quality of Life Diabetic Neuropathy (Norfolk QoL-DN) questionnaire. Group differences were analyzed with analysis of covariance and correlations with Pearson's coefficients. RESULTS:HTS parameters (Touch Duration, Inter-Tapping Interval, Movement Rate) significantly differed across stages between the FAP2 and all other groups, with some parameters distinguishing the FAP1 from the control and FAP0 groups. 9HPT impairment was observed only in the FAP2 group. Grip strength showed subtle changes, especially in the right hands of the FAP1 group, while tripod pinch strength declined during advanced stages. Several HTS parameters were correlated with NIS, DASH, Norfolk QoL-DN, and hand strength. Subclinical carpal tunnel syndrome possibly influenced early-stage results. INTERPRETATION:HTS detected stage-related motor differences in ATTRv and correlated them with standard measures, offering increased sensitivity to early neuropathic changes.

BACKGROUND:The F64L variant is among the most frequent TTR mutations in Italy, typically associated with a predominantly neurologic phenotype and limited cardiac involvement. METHODS:Data from 181 ATTRv patients in the multicenter Patisiranitaly database treated with Patisiran since 2020 were analyzed. Neurologic impairment scores, Norfolk QoL-DN, and cardiac parameters were compared between F64L (n = 56), V30M (n = 37), and non-F64L (n = 125) patients at baseline and during follow-up. Cluster analysis was applied to identify patient subgroups based on these variables. RESULTS:F64L represented 30.9% of the cohort. Compared to non-F64L patients, F64L patients had a higher prevalence of neurologic onset and neurologic phenotype, a thinner interventricular septum, and lower NT-proBNP levels. Cluster analysis segregated patients into two distinct groups, predominantly reflecting F64L vs. non-F64L status and corresponding neurologic severity. F64L patients showed milder cardiac involvement compared to V30M patients. Longitudinal repeated-measures ANOVA showed stable clinical and instrumental measures. CONCLUSIONS:F64L is characterized by predominant neurologic involvement and milder cardiac involvement in this Patisiran-treated cohort. Mutation-specific diagnostic and follow-up strategies are essential to capture its natural history and treatment response.

BACKGROUND AND OBJECTIVES:Phosphorylated TAR DNA-binding protein 43 (pTDP-43) is the pathologic hallmark of amyotrophic lateral sclerosis (ALS), yet no peripheral premortem biomarker is available. We evaluated pTDP-43 distribution in skin and tongue tissues and its association with ALS and clinical stage. METHODS:This cross-sectional case-control study included patients with ALS meeting revised El Escorial criteria who underwent skin and tongue biopsies. Control groups included healthy controls (HC), patients with non-ALS neuropathy or neuronopathy (NANN), and patients with burning mouth syndrome (BMS). pTDP-43 was quantified in Meissner corpuscles (MC) and keratinocytes using standardized immunofluorescence. In MC, PGP (%), pTDP-43 (%), and the pTDP-43/PGP ratio were assessed. A subset of skin samples underwent western blot analysis. ALS severity was classified using King's staging system. Diagnostic performance was evaluated using receiver operating characteristic analysis. RESULTS:Fifty patients with ALS were included, median age 66.5 years, 36% female. Control groups included 20 HC, median age 60 years, 20% female, and 20 patients with NANN, median age 60 years, 50% female. Tongue biopsy was performed in 10 patients with ALS and 10 patients with BMS. pTDP-43 deposits were detected in ALS across epidermis and dermis structures, whereas they were almost absent in HC and low in NANN. Accordingly, MC pTDP-43% differed across groups (H = 53.30; p < 0.001), with median values of 0.35 (interquartile range [IQR] 0.39) in ALS, 0.04 (IQR 0.03) in NANN, and 0.00 in HC. The pTDP-43/PGP ratio increased with clinical stage at subject level (Z = 2.20, p = 0.028) and single-corpuscle level (H = 21.72, p < 0.001). Western blot showed higher pTDP-43/GAPDH ratio in ALS skin than in HC (median 3.45, IQR 7.23 vs 1.30, IQR 0.80; p = 0.007). Nonphosphorylated TDP-43 did not differ across groups. In keratinocytes, pTDP-43 was higher in ALS than in NANN and HC (median 0.047, IQR 0.023; 0.019, IQR 0.049; and 0.005, IQR 0.047; p < 0.001). Combined cutaneous pTDP-43 measures discriminated ALS from HC (area under the curve [AUC] 0.94, p < 0.001) and from NANN (AUC 0.90, p < 0.001). Tongue biopsies showed pTDP-43 aggregates in intramuscular nerves, denervated endplates, and muscle fibers. DISCUSSION:Peripheral pTDP-43 deposition distinguishes ALS from controls and reflects disease stage, supporting its potential role as a biomarker of ALS and disease severity. Larger and longitudinal studies are required for validation.

Hypermobile Ehlers-Danlos syndrome (hEDS), frequently presents with pain and autonomic symptoms suggestive of small fiber neuropathy (SFN). However, systematic comparisons between hEDS and idiopathic SFN (iSFN) using combined clinical, functional, and morphological approaches are lacking. We prospectively studied a population of SFN patients who also fulfilled the 2017 criteria for hEDS (hEDS/SFN) and compared them with a group of iSFN patients of similar age. All underwent SFN-Symptoms Inventory Questionnaire (SFN-SIQ), Douleur Neuropathique 4 (DN4), and the Composite Autonomic Symptom Score-31 (COMPASS-31) questionnaires, quantitative sensory testing (QST), autonomic testing (cardiovascular reflexes, sympathetic skin response, dynamic sweat test), and skin biopsy from leg, thigh, and fingertip. Clinical, morphological and functional data were compared with our normative dataset and between the two patient groups. 35 hEDS/SFN and 38 iSFN patients were included in the study. hEDS/SFN patients had earlier symptom onset (19.5 ± 5.9 years vs. 35.2 ± 8.7 years, p < 0.001), more generalized distribution, and higher COMPASS-31 scores (54.3 ± 16.9 vs. 33.9 ± 19.4 p < 0.01), particularly in orthostatic intolerance, gastrointestinal, and urinary domains. Postural Orthostatic Tachycardia Syndrome (POTS) was present in half of hEDS/SFN patients while it was not found in iSFN (51.5% vs. 0.0%). Skin biopsy revealed similar intraepidermal nerve fiber loss in both groups, but hEDS had greater autonomic fiber loss (p < 0.05). Small fiber involvement in hEDS is characterized by earlier onset, more generalized pain and severe autonomic symptoms, and higher autonomic morpho-functional impairment compared with iSFN. Systematic autonomic assessment and targeted management should be considered in this population.

Sphingolipids are integral components of cell membranes and modulate cell survival, proliferation, and apoptosis. ASAH2 is a brain-and gut-enriched gene encoding the neutral N-acylsphingosine amidohydrolase 2, a poorly characterized member of the human ceramidase family. This enzyme plays a pivotal role in maintaining the sphingolipid homeostasis, which is crucial for neurogenesis and synaptic function in the central and peripheral nervous systems. In fact, a dysregulated sphingolipid metabolism is associated with progressive neurological conditions, including Alzheimer disease and Parkinson disease. Here, we report the identification of biallelic ASAH2 variants in an individual with a neurodevelopmental condition featuring cognitive impairment, neuropathy, ophthalmoplegia, and progressive cerebellar and extraocular muscles atrophy. Through exome sequencing, we identified very rare missense ASAH2 variants, predicted to be deleterious by in silico analyses. Muscle biopsy histopathologic evaluation revealed features suggestive of neuropathic damage. Lipidomic profiling revealed a hyper-accumulation of glucosylceramide in the subject's cells. Then, the functional investigation of the ASAH2 variants in Drosophila showed the production of an unstable protein and consistent loss-of-function neuromotor phenotypes. Our findings support ASAH2 as a candidate gene for a previously uncharacterized neurodevelopmental disorder with neuropathic features and progressive cerebellar atrophy, underscoring the important role of this ceramidase in human nervous systems.

Polyneuropathies are common and often require specialist expertise for accurate diagnosis. This study evaluated the diagnostic performance of ChatGPT-4o on real-world polyneuropathy cases, comparing it to peripheral neuropathy specialists and non-specialist neurologists. One hundred cases were selected from two tertiary centers in Milan, Italy. Standardized summaries included clinical, laboratory, and electrophysiological data. ChatGPT-4o was prompted to provide a leading diagnosis, two differentials, and a confirmatory test. Neurologists reviewed the same cases and generated comparable outputs, then could revise their responses after viewing ChatGPT-4o's suggestions. ChatGPT-4o achieved 65.5% leading diagnosis accuracy, comparable to non-specialists (63.0%) but lower than specialists (74.0%, p = 0.002). For differential diagnoses, it outperformed non-specialists (82.0% vs. 77.5%, p = 0.043) and recommended more appropriate tests (68.0% vs. 53.0%, p < 0.001). After reviewing ChatGPT-4o outputs, non-specialists revised their assessments in 21.8% of cases, improving accuracy. ChatGPT-4o shows potential as a diagnostic aid, particularly in non-specialist or resource-limited settings.

Background and Objectives:Anesthetic management for Charcot-Marie-Tooth disease (CMT) is still controversial and source of concerns for both anesthetists and patients. We explored the frequency of self-reported complications following anesthesia in a large cohort of patients with CMT compared with unaffected controls. Methods:We administered an online ad hoc questionnaire to patients enrolled in the Italian CMT Registry and to unaffected controls. The questionnaire collected self-reported adverse events following any anesthetic procedure undergone during the participants' lifetime. Anesthetic procedures were categorized as general anesthesia (including endotracheal intubation or deep sedation), central neuraxial anesthesia (epidural or spinal anesthesia), and peripheral regional anesthesia (plexus or peripheral nerve blocks). Results:Overall, the questionnaire was completed by 290 patients with CMT (160 female patients; mean age 47.8 ± 13.1 years) and 94 controls (46 female patients; mean age 47.5 ± 13.2 years), and a total of 508 and 161 procedures, respectively, were analyzed. The rate of self-reported complications following general, central neuraxial, and peripheral regional anesthesia did not differ between patients with CMT and controls. All reported events in the CMT cohort were transient and fully resolved, with a favorable anesthetic outcome in all cases. Demyelinating CMT subtypes were not more likely to report complications than axonal subtypes. Moreover, experienced complications following anesthesia for cesarean delivery occurred with similar frequency in patients with CMT and controls. Discussion:Anesthesia-related complications are not reported more frequently in patients with CMT compared with controls. However, longitudinal studies incorporating objective clinical assessments and detailed information on anesthetic agents are warranted.

Biallelic mutations in the sorbitol dehydrogenase (SORD) gene have been identified as one of the most common causes of autosomal-recessive Charcot Marie Tooth disease type 2 (CMT2) and distal hereditary neuropathy, collectively referred to as SORD deficiency. These mutations result in loss of sorbitol dehydrogenase activity, a key enzyme in the polyol pathway that metabolizes glucose, leading to marked accumulation of sorbitol in patient derived fibroblasts. However, the mechanisms by which SORD dysfunction drives axonal degeneration remain poorly understood, and robust in vitro models of human SORD deficient motor neurons (MNs) are still lacking. To address this gap, we established a human in vitro model of SORD deficiency by generating induced pluripotent stem cells (iPSCs) from fibroblasts affected individual carrying biallelic SORD mutations (SORDc.757delG/c.316_425+165del), and unaffected heterozygous carriers (SORDc.757delG/wt and SORDwt/c.316_425+165del). These iPSCs were subsequently differentiated into motor neuron progenitors (MNPs) and MNs. Comprehensive analysis of SORD-deficient human cells, including fibroblasts, MNPs, and MNs, revealed pronounced structural and functional abnormalities in the mitochondrial compartment, characterized by mitochondrial fragmentation and increased proton leak. Importantly, fibroblasts derived from two additional unrelated patients carrying the SORD mutation (SORDc.757delG/ c.757delG) further confirmed that SORD deficiency is associated with a mitochondrial phenotype. At the molecular level, SORD deficiency led to upregulation of aldose reductase (AR), another key enzyme of the polyol pathway, resulting in disruption of cellular redox homeostasis and increased oxidative stress. Consistent with these alterations, MNs derived from CMT2/SORD patients exhibited clear neurodegenerative features, including severe defects in neurite branching and synaptic architecture, ultimately impairing neuronal connectivity. Notably, pharmacological inhibition of AR effectively rescued both mitochondrial dysfunction and neuronal structural defects, supporting the targeting of AR as a promising therapeutic strategy for polyol pathway associated neuropathies as CMT2/SORD and diabetic neuropathy.

Biallelic loss-of-function mutations in the sorbitol dehydrogenase (SORD) gene cause the most common recessive type of Charcot-Marie-Tooth disease (CMT), CMT-SORD. However, the full genotype-phenotype spectrum and progression of the disease remain to be defined. Notably, a multicentre phase 2/3 study to test the efficacy of govorestat (NCT05397665), a new aldose reductase inhibitor, is currently ongoing. Diagnosing CMT-SORD will become imperative when disease-modifying therapies become available. In this cross-sectional multicentre study, we identified 144 patients from 126 families, including 99 males (69%) and 45 females (31%). Patients represented multiple ancestries, including European, Hispanic, Chinese, Near Eastern and Northern African. We confirmed c.757delG (p.Ala253GlnfsTer27) as the most common pathogenic allele, followed by c.458C>A (p.Ala153Asp), while other variants were identified, mostly in single cases. The average sorbitol level in CMT-SORD patients was significantly higher compared to controls and heterozygous carriers, independently from serum storage duration, sex or variant type. Two-thirds of cases were diagnosed with CMT2 while one-third had distal hereditary motor neuropathy. Disease onset was usually in the second decade of life. Although foot dorsiflexion was the most affected muscle group, dorsal and plantar flexion had a similar degree of weakness in most cases (difference of Medical Research Council score <= 1). One-fourth of patients used ankle foot orthoses, usually in their 30s, but most patients maintained independent ambulation later in life. Nerve conduction studies were suggestive of a motor predominant axonal neuropathy, with reduced conduction velocities in the intermediate range in a quarter of the cases. Sensory conductions in the upper limbs appeared more frequently affected than in the lower limbs. Foot dorsiflexion and plantar flexion decreased significantly with age. Male sex was significantly associated with the severity of distal lower limb weakness (plantar flexion) and a larger change over time (dorsiflexion). In conclusion, CMT-SORD is a frequent recessive form of axonal, motor predominant CMT, with prominent foot dorsiflexion and plantar flexion involvement. Fasting serum sorbitol is a reliable biomarker of the condition that can be utilized for pathogenicity assessment of identified rare SORD variants.

Background and Objectives:Myelin protein zero (MPZ)-related neuropathies include demyelinating CMT1B and later-onset axonal forms (CMT2I/J). CMT1B pathogenic variants act through gain-of-function, destabilizing MPZ and activating the unfolded protein response (UPR), or loss-of-function, disrupting MPZ homomeric interactions in myelin. This study investigates early-onset (<18 years) CMT1B due to MPZ variants in a large Italian cohort, shedding light on clinical progression and genotype-phenotype correlations, with relevance to emerging UPR-targeted therapies. Methods:We analyzed cross-sectional clinical and genetic data from 75 patients across 7 Italian centers. MPZ variants were categorized as destabilizing or non-destabilizing based on published data. To explore the relationship between the degree of protein destabilization and clinical severity, missense variants were evaluated for stability alterations using the DUET online tool, with negative ∆∆G values indicating greater destabilization. Statistical correlations between clinical and molecular features were assessed. Results:This study presents a comprehensive clinical characterization of one of the largest cohorts of early-onset MPZ-related neuropathies reported to date. The Charcot-Marie-Tooth Examination Score (CMTES) correlated with age at assessment (r s = 0.56; p < 0.001), suggesting disease progression in this cohort. Destabilizing variants were associated with earlier onset (p < 0.001), upper limb involvement (p < 0.001), impaired ambulation (p < 0.01), scoliosis (p < 0.01), and faster progression as measured by CMTES/age (0.24 vs 0.11 CMTES/year). After excluding the c.245A>C, p.Y82S outlier (highly destabilizing but not UPR-activating), ∆∆G values showed significant correlations with age at onset (r s = 0.54, p = 0.030), CMTES (r s = -0.82, p < 0.001), and progression (r s = -0.60, p = 0.032). Discussion:Stratification of MPZ variants into destabilizing and non-destabilizing is crucial for predicting severity and prognosis and tailoring therapeutic strategies. This approach has significant implications for upcoming UPR-modulating treatments and underscores the necessity of integrating molecular and clinical insights for optimal patient care.

ABSTRACT Background and Aims In 2019, we conducted a cross‐sectional study, collecting information on 50 patients with CMT4B, an ultrarare CMT subtype, to better define the clinical phenotype. We now aimed at investigating disease progression in 26 patients with CMT4B1/CMT4B2, recruited from the previous study and among the Inherited Neuropathy Consortium. Materials and Methods We retrospectively analysed disease progression in patients with CMT4B1/CMT4B2, collecting MRC scores from nine muscle pairs, Charcot‐Marie‐Tooth Examination Score (CMTES), and a minimal dataset of clinical information (walking difficulties, aids dependency, upper limb impairment, cranial nerves involvement) at baseline and follow‐up visits. Thirteen centres from four continents were involved. Results Thirteen CMT4B1 and 13 CMT4B2 patients were followed up for 7.1 ± 4.9 and 7.9 ± 4.5 years, respectively. During follow‐up, walking aid dependency increased: two CMT4B1 patients adopted AFOs (overall 11/12 at follow‐up), and one started using wheelchair (6/12 at follow‐up) at the age of 19; among CMT4B2 patients, two more required unilateral support in walking (4/11 at follow‐up) by the age of 33 and 49 years, respectively. We found that disease progression, as measured by CMTES, was faster in CMT4B1 as compared to CMT4B2 patients (ΔCMTES/year 0.7 vs. 0.3, p = 0.037) but tended to slow down over time as burden of disease increased. At the end of follow‐up, CMT4B1 was associated to higher disability. Conclusions This international collective effort enabled collection of relevant data for characterizing natural history and estimating disease progression of CMT4B1/CMT4B2 ultrarare diseases, aiming at improving their management and paving the way for designing future clinical trials.