Rocco Liguori

Background: α-synuclein (Lewy body-type) co-pathology has been identified at autopsy in a subset of patients with amyotrophic lateral sclerosis (ALS). However, its prevalence and prognostic relevance in vivo remain poorly characterized. Methods: We analyzed baseline cerebrospinal fluid (CSF) α-synuclein seed amplification assay (αSyn SAA) status in 443 patients with ALS from two cohorts (Nagoya, Japan, n = 248; Bologna, Italy, n = 195). Samples were classified as strong-positive, weak-positive, or negative based on RT-QuIC reactivity across replicate wells, using the assay’s established a priori criteria at initial and repeat testing; classifications were corroborated by quantitative kinetic parameters. We compared age– and sex-adjusted odds of positivity in ALS with those in cognitively unimpaired (CU; n = 999; stratified by amyloid-β [Aβ] status), Aβ-positive mild cognitive impairment ( n = 224), and Alzheimer’s disease dementia ( n = 319) groups from the Swedish BioFINDER cohort. In ALS, we examined tracheostomy-free survival and longitudinal functional decline using cohort-stratified Cox and linear mixed-effects models, respectively. We also assessed interactions between αSyn SAA status and baseline CSF neurofilament light chain (NfL). Prognostic analyses were performed in sporadic ALS and repeated after including familial or genetic cases. Results: Strong αSyn SAA positivity was detected in 24/443 patients with ALS (5.4%); overall positivity, including weak-positive samples, was 37/443 (8.4%). Patients with ALS did not have significantly higher odds of SAA positivity than Aβ-negative CU participants (age– and sex-adjusted odds ratio [OR] 1.33, 95% CI [0.82, 2.14]) and had significantly lower odds than patients with Alzheimer’s disease dementia (OR 0.44, [0.27, 0.70]). Among patients with sporadic ALS, strong αSyn SAA positivity was associated with shorter tracheostomy-free survival after adjustment for established predictors including NfL (adjusted HR 2.08 [1.25, 3.45]), whereas weak positivity showed no clear survival association. In linear mixed-effects models, strong αSyn SAA positivity modified the association between NfL and ALSFRS-R decline (NfL × αSyn SAA × time interaction β−0.70 points/month [−1.26, −0.14] per SD NfL). These findings persisted in analyses including familial or genetic ALS cases and in those restricted to Aβ-negative patients. Neuropathological findings ( n = 5) were concordant with the CSF αSyn SAA classification. Conclusions: A strong α-synuclein seeding profile was uncommon in ALS but identified a subgroup with shorter survival and a stronger association between NfL and functional decline. These findings provide ante-mortem evidence that α-synuclein co-pathology may contribute to prognostic heterogeneity in ALS.

Background and ObjectivesAntibody testing has a pivotal role in the diagnosis of myasthenia gravis (MG). However, there are limited data on the accuracy of the different methods available for acety...

Objective: To determine whether ordinal Subtype and Stage Inference (SuStaIn) applied to routine ALSFRS‐R item scores can identify reproducible disability progression patterns in amyotrophic lateral sclerosis (ALS) and provide clinically meaningful staging. Methods: We analysed baseline ALSFRS‐R item responses from 866 PRO‐ACT participants. Ordinal SuStaIn inferred subtype‐specific sequences of functional deterioration and assigned each participant to a subtype and a SuStaIn‐derived functional stage. Longitudinal stability was assessed across 3625 consecutive follow‐up visit pairs from 697 participants. Structural reproducibility was evaluated in an independent cohort of 301 consecutive ALS patients. Associations of baseline subtype and stage with survival and subsequent ALSFRS‐R decline were examined using Cox and piecewise‐linear models. Results: A three‐subtype solution identified fine motor‐, gross motor‐ and bulbar‐predominant patterns of early disability. Within each subtype, SuStaIn reconstructed ordered multidomain sequences of functional deterioration and assigned each participant a SuStaIn‐derived stage. Subtype assignment was stable across 90.4% of consecutive visit pairs, and stage was non‐decreasing in 98.8%. Subtype‐specific event ordering was reproduced in the validation cohort. Higher baseline stage was associated with increased mortality risk in the fine motor‐ and gross motor‐predominant subtypes, but not clearly in the bulbar‐predominant subtype. Baseline stage showed subtype‐dependent, non‐linear associations with subsequent functional decline, with acceleration up to mid‐stage breakpoints in the fine motor‐ and gross motor‐predominant subtypes and less evident stage‐dependent acceleration in the bulbar‐predominant subtype. Interpretation: Routine ALSFRS‐R item‐level data can define clinically interpretable ALS progression subtypes and latent SuStaIn‐derived functional stages. Joint subtype‐stage modelling may refine prognostic stratification and support prognosis‐informed trial enrichment.

We present a family of five siblings who came to our attention with a clinical and radiological diagnosis of familial hypomyelinating leukodystrophy. Despite brain white matter abnormalities being present in all siblings, the clinical phenotype was variable: the three brothers presented with a clear-cut late-onset spastic paraplegia, whereas the two sisters displayed only mild pyramidal signs. Molecular analysis revealed a single relevant variant shared by all affected siblings, namely the likely pathogenic variant c.659C>T (p.Ser220Phe) in the GJA1 gene. Variants in this gene are generally associated with oculodentodigital dysplasia (ODDD), an autosomal dominant condition characterized by distinctive facial features and anomalies of the eyes, teeth, and digits. Neurological features are reported in about 30% of cases. In this family, ODDD manifested as a predominantly neurological phenotype. Although a clear explanation for this uncommon presentation is lacking, shared genetic modifiers, the effect of the specific variant, and a possible patient-population bias may have contributed. This case highlights the wide phenotypic spectrum of CX43-related disorders and suggests the importance of testing the GJA1 gene in individuals with atypical presentations, including predominant or isolated neurological phenotypes such as late-onset spastic paraplegia. MRI findings may also provide a useful diagnostic clue when ODDD is suspected.

We present a comprehensive molecular and histopathological characterization of nine patients with mitochondrial myopathy, predominantly manifesting progressive external ophthalmoplegia (PEO), associated with heteroplasmic variants in mitochondrial tRNA genes (mt-tRNA). Among the ten variants identified, four were novel and previously unreported in MITOMAP. Using laser capture microdissection and deep next-generation sequencing, we quantified heteroplasmy at the single-muscle-fibre level, demonstrating that cytochrome c oxidase (COX)–deficient fibres consistently reached near-homoplasmic mutant loads, whereas COX-positive fibres remained heteroplasmic with lower variant fractions. These findings firmly support the pathogenic role of all variants. Furthermore, digital droplet PCR revealed an increased mitochondrial DNA (mtDNA) content in COX-deficient fibres, indicating compensatory mitochondrial biogenesis. Of particular note, one patient harboured two novel heteroplasmic variants, m.10009G > A and m.15961G > A, for which long-read sequencing identified mitogenomes carrying both variants also in cis, suggesting the occurrence of mtDNA recombination in human tissue. By applying refined American College of Medical Genetics and Genomics (ACMG) criteria specific for mt-tRNA, we reclassified several variants as pathogenic or likely pathogenic, including three previously deemed of uncertain significance. Overall, our integrative approach—combining single-fibre molecular dissection, mtDNA quantification, and long-read sequencing—broadens the mutational spectrum of pathogenic mt-tRNA variants, highlights the diagnostic value of single-fibre analyses in confirming pathogenicity, and provides new insights into mitochondrial genome dynamics and compensatory responses in mitochondrial disease.

Myasthenia gravis (MG) is an autoimmune disorder primarily caused by antibodies targeting neuromuscular junction proteins, particularly the acetylcholine receptor and the muscle-specific tyrosine kinase. However, 10%-20% of patients with MG are double-seronegative (dsMG). Antibodies against low-density lipoprotein receptor-related protein 4 (LRP4-IgG) have been found in a variable proportion of dsMG cases, but their frequency and clinical relevance remain unclear because of differences in assay methodologies and study populations. In this study, we assessed the frequency of LRP4-IgG in patients with suspected MG using different cell-based assay (CBA) protocols. In this multicenter observational study, we enrolled consecutive patients presenting with symptoms suggestive of MG. LRP4-IgG was tested by 2 centers using 3 different CBAs: live (l-CBA), methanol-fixed (mf-CBA), and paraformaldehyde-fixed (pf-CBA). Patients were classified as having MG or other disorders (ODs). Positive samples were cross-tested between centers. Among 684 patients (302 with MG, 382 with ODs), LRP4-IgG was detected by mf-CBA in 2% (6/302) of MG cases and in 0.52% (2/382) of OD cases. Among patients with MG, 3.9% (4/102) of dsMG and 1% (2/200) of seropositive patients tested positive. Only 50% of mf-CBA-positive cases were confirmed by pf-CBA, and none were detected by l-CBA. Cross-center testing showed partial reproducibility. LRP4-IgG detection in suspected MG is rare and inconsistent across assays, suggesting that routine testing is not currently warranted and that these antibodies are at present of limited diagnostic value. These findings highlight the need for standardized, validated LRP4-IgG assays. Future studies should focus on direct comparison and harmonization of testing protocols to clarify the clinical utility of LRP4-IgG testing.

This report details a pediatric case of myelin oligodendrocyte glycoprotein antibody disease (MOGAD) characterized by isolated MOG-IgG3 positivity and IgG1 deficiency, highlighting a unique serologic profile and exploring its immunologic significance. In addition, a review of MOGAD cases with isolated MOG-IgG3 antibodies is included. A 12-year-old boy presenting with a progressive neurologic syndrome underwent clinical, radiologic, and laboratory evaluation. MRI showed extensive brain and spinal lesions. MOG-IgG3 antibodies were identified in serum and CSF by live cell-based assay, while other MOG-IgG subclasses were not detected. Serum IgG1 was low at baseline and throughout follow-up. First-line immunotherapy treatment led to significant improvement, with no relapses at 2-year follow-up. This case highlights the potential role of subclinical IgG1 deficiency in shaping the predominance or selective detection of MOG-IgG3 in MOGAD. While most MOG antibodies are predominantly of the IgG1 isotype, our review identified a few cases with isolated MOG-IgG3 antibodies. A possible contribution to pathogenesis cannot be excluded, and the patient's inability to produce a balanced IgG subclass profile could have favored a sustained IgG3 response. Larger studies are needed to clarify the clinical significance of MOG-IgG3 in MOGAD.

Neuromuscular diseases (NMDs) include a heterogeneous group of progressive chronic conditions that frequently lead to substantial physical disability and loss of autonomy. Although motor and functional impairments of NMDs are well documented, the psychological burden remains underexplored. This narrative review synthesizes current literature regarding four psychological domains in individuals with NMDs: (i) anxiety, (ii) depression, (iii) coping strategies, and (iv) quality of life. Evidence indicates that anxiety and depressive symptoms are highly prevalent in the spectrum of NMDs, influenced by factors such as disease severity, onset age, and perceived social support. Maladaptive coping strategies, including avoidance and denial, are associated with poorer mental health outcomes and reduced involvement in rehabilitation. In contrast, adaptive strategies, such as acceptance and problem-focused coping, may help buffer psychological distress. Quality of life is consistently reported to be lower in people with NMDs compared to the general population, with psychosocial factors such as social support playing a role. Despite these findings, psychological care remains inconsistently integrated in NMD management.

Skin biopsy is an affordable, minimally invasive technique that provides direct access to peripheral neural structures for in vivo evaluation of cutaneous nerve pathology, with relevance to both peripheral and central nervous system disorders. Skin biopsy allows the assessment of somatic and autonomic fibers as well as their innervated structures, representing the gold standard for the diagnosis of Small-Fiber Neuropathy. Nonetheless, the assessment of autonomic fibers remains challenging, as the patterns of sympathetic and parasympathetic skin innervation have not yet been fully elucidated, and the intricate organization of effector structures (e.g., arrector pilorum muscles, sweat glands, blood vessels) poses methodological difficulties. Beyond small-fiber evaluation, skin biopsy allows the detection of disease-specific deposits of abnormally accumulating proteins in a broad spectrum of clinical entities. It has proven highly accurate in detecting synucleinopathies in vivo, with near-complete specificity in the discrimination of affected patients from healthy controls and from alternative neurodegenerative disorders. Furthermore, the pattern of α-synuclein deposition serves to differentiate Lewy body from non-Lewy body synucleinopathies, thereby distinguishing disorders with similar clinical manifestations but distinct physiopathology and prognostic implications. In this narrative review, we outline the current indications for skin biopsy in the evaluation of diverse neurological disorders and address the main methodological aspects of the technique.

We report a case of hereditary sensory and autonomic neuropathy presenting with childhood-onset symmetric distally predominant limb hypoesthesia to tactile, thermal, and painful stimuli. Exome sequencing identified a homozygous pathogenic variant in the with-no-lysine (K) kinase 1 (WNK1), lysine deficient protein kinase 1 gene. The clinical, electrophysiological, and genetic findings confirmed a diagnosis of hereditary sensory and autonomic neuropathy type 2A (HSAN 2A). This case highlights the importance of genetic confirmation in the evaluation of early-onset neuropathies, especially when the most common causes have been ruled out. Significantly, our observations underscore the potential role of skin biopsy in identifying autonomic abnormalities in HSAN 2, possibly contributing to a better understanding of these rare neuropathies. We also reviewed the reported cases of this disease in the literature to highlight its phenotypic variability.