Neurology-Genetics最新文献

Background and objectives: Hereditary cerebellar ataxia (HCA) and hereditary spastic paraplegia (HSP) are rare neurologic disorders that often represent opposite ends of a shared clinical spectrum. Spastic ataxia, defined by the co-occurrence of cerebellar syndrome and overt spasticity, remains comparatively underexplored and is associated with relatively few genetic causes. The aim of this study was to characterize the clinical and genetic features of spastic ataxia in a large HCA cohort and compare them with those of nonspastic HCA.

Methods: A prospective HCA cohort was initiated in 2017, incorporating annual assessments following a structured and standardized protocol. Spastic ataxia was defined as ataxia occurring in conjunction with spasticity grade ≥2 on the Modified Ashworth Scale. Patients meeting this criterion were identified; their clinical and genetic data were analyzed and compared with those of patients with nonspastic forms of HCA. The Movement Disorder Society's nomenclature for genetic disorders was adopted, using dual-prefix notation for combined phenotypes (e.g., HSP/ATX for spastic ataxia), except for entities such as MJD/SCA3 or ARSACS, which are more readily recognized by their original designations.

Results: Of 249 patients assessed (164 families), 56 (22.5%; from 46 families) exhibited a spastic ataxia phenotype. Compared with nonspastic HCA, these patients had earlier onset and longer disease duration. Spastic ataxia was significantly associated with autosomal recessive inheritance and conventional (nonrepeat expansion) variants. Thirty-eight probands (80.8%) had a definite genetic diagnosis, involving 22 causal genes. The most frequent diagnoses were ARSACS (17.4%), ATX-SYNE1 (6.5%), ATX-ANO10, HSP/ATX-KIF1C, HSP/ATX-PGN, HSP-ZFYVE26, MxMD-ATP13A2, and ATX/HSP-KCNA2 (4.3% each). A noncerebellar presentation was observed in 30 patients with spastic ataxia (53.6%) while 26 (46.6%) had cerebellar onset. After adjustment for disease duration, patients with spastic ataxia had significantly higher baseline scores on the Scale for the Assessment and Rating of Ataxia, reflecting a greater disease burden. In addition, falls were more frequent in this group.

Discussion: Spastic ataxia represented a clinically and genetically distinct subgroup within HCA, marked by recessive inheritance, large genetic heterogeneity, and more severe motor impairment. Greater awareness of its heterogeneous presentations and progressive disability over time is crucial for timely diagnosis, genetic counseling, and development of tailored management strategies for these patients.

Background and objectives: SYNE1 deficiency is an autosomal recessive disorder with a broad phenotypic spectrum, most commonly presenting as adult-onset cerebellar ataxia with or without motor neuron dysfunction. We aimed to expand this spectrum by describing the clinical and genetic findings in 2 unrelated families with early-onset motor neuron disease and virtually no cerebellar signs over time.

Methods: We performed detailed clinical, neurophysiologic, and genetic studies of 2 unrelated families with juvenile amyotrophic lateral sclerosis (ALS) and biallelic variants in SYNE1.

Results: The phenotypes of both families showed onset of symptoms in childhood or adolescence, with signs of upper and lower motor neuron dysfunction in multiple territories suggestive of juvenile ALS. Patients developed progressive muscle weakness, eventually leading to respiratory distress and bulbar signs. Whole-exome sequencing identified SYNE1 biallelic truncating variants in both families: a homozygous nonsense variant, c.23131C>T (p.Gln7711*), in Family 1, and a novel homozygous splice-site variant, c.17851-1G>A, in Family 2. Notably, mild or no cerebellar manifestations were observed during the follow-up.

Discussion: This report highlights a novel phenotype of SYNE1 deficiency characterized by early-onset motor neuron disease and virtually no cerebellar manifestations, broadening the phenotypic spectrum of this complex neurodegenerative disease. These findings support investigating SYNE1 variants in juvenile ALS and including SYNE1 in motor neuron disease gene panels.

A recent explosion in genomic testing has led to the identification of several genetic disorders that mimic CNS-specific autoimmune disorders. Such monogenic disorders, although rare, represent a diagnostic challenge because of their diverse phenotypes and overlapping features. Early recognition of these disorders is crucial not only to prevent overtreatment with immunotherapy but also to ensure that targeted treatments are available for many of these disorders. This review explores some of the monogenic disorders that can masquerade as neuroinflammatory phenotypes. These clinical vignettes are stratified according to neuroanatomical localization along the neuroaxis: supratentorial white matter, gray matter, brainstem, and spinal cord involvement. Through these cases, we discuss how clinical, laboratory, and neuroimaging red flags, such as early onset, relentless progression despite immunotherapy, and lack of CSF markers of inflammation, can guide specific diagnostic workup. In the next section, we highlight the approach to genetic testing in identifying monogenic mimickers. Finally, we discuss a selected list of currently available and emerging therapeutic strategies for some of these disorders. These include JAK inhibitors for Aicardi-Goutières syndrome, anti-TNF therapy for adenosine deaminase 2 deficiency (DADA2), and gene replacement therapy for X-linked adrenoleukodystrophy. By providing a comprehensive and systematic clinical approach, this review aims to equip neurologists with a framework to navigate diagnostic evaluations for such monogenic disorders.

Background and objectives: PTEN hamartoma tumor syndrome (PHTS) is an autosomal dominant cancer predisposition and overgrowth syndrome due to pathogenic germline variants in the PTEN gene. PHTS harbors a diverse range of clinical manifestations including an associated neurodevelopmental (ND) and neurologic phenotype, requiring a multidisciplinary approach to care. There are no clinical practice guidelines for the management of ND or neurologic comorbidities. The objective of these clinical guidelines was to use the latest knowledge to generate a resource for providers, researchers, and patients on the best practices in the practical management of neurologic and ND challenges in PHTS.

Methods: The PHTS Consensus Guidelines Working Group was established, comprising a core group of seven experts in the diagnosis and management of PHTS, including genetics, neurology, neuropsychology, and neurodevelopment (including psychiatry and psychology). The Working Group held joint meetings with a Patient Advisory Group (PTEN Foundation), comprising patients with PHTS and their advocates. Informed by a comprehensive literature review, the Working Group met regularly between 2022 and 2024 to produce guideline statements, refined through iterative feedback. A modified Delphi approach was used with an independent extended panel of neurologists, neuropsychologists, and psychiatrists, to establish final consensus guidelines.

Results: The first iteration of the clinical consensus recommendations for the management of ND and neurologic features in patients with PHTS was formed. Guidelines encompass ND challenges, mood disorders, ND screening, neuroimaging abnormalities, neurologic comorbidities, and tumors affecting the CNS.

Discussion: While multiple efforts are ongoing to better characterize the natural history of PHTS, the clinical management of individuals with PHTS is complex and remains challenging because of variable expressivity and age-related specificities. As part of a comprehensive effort to develop consensus management guidelines, which cover all manifestations of PHTS, we present the first iteration of guidelines for the ND and neurologic manifestations of PHTS, aimed at improving care for affected individuals and families.

Background and objectives: Cerebral white matter hyperintensities (WMHs) on MRI are part of the spectrum of age-related brain vascular injury and are associated with increased risk of stroke and dementia. Genome-wide association studies (GWASs) conducted mostly in populations of European ancestry have identified several genetic loci. Although Hispanic/Latino adults have a greater burden of WMHs than their non-Hispanic White counterparts, they are vastly underrepresented in genetic studies. We sought to characterize the genetic architecture of WMHs in a Hispanic/Latino cohort by investigating the transferability of known WMH genetic loci and by leveraging Hispanic/Latino genetic diversity to map novel loci.

Methods: We conducted genome-wide association and admixture mapping analyses of WMH volume in a sample of 2,159 diverse Hispanic/Latino adults (mean age: 62.4 years; 66% female). We investigated associations at 27 previously identified WMH loci. To identify additional loci, we meta-analyzed our genome-wide association results with those of the largest GWASs published to date.

Results: Accounting for population differences in linkage disequilibrium, we found some evidence of transferability of 20 of the 27 known WMH loci. Owing to power limitations, we could not exclude transferability of the remaining loci. Multiancestry meta-analysis combining our Hispanic/Latino genome-wide association results with those from a GWAS of non-Hispanic White (NHW) and African American (AA) populations identified a novel locus on 12q22 (p = 1.8 × 10^-8) near NTN4 and tagged by rs10859915, which was previously associated with blood pressure and is an expression quantitative trait locus of AMDHD1. Admixture mapping identified a novel locus on 14q13.2, where higher counts of European ancestry at that locus were significantly associated with higher WMH volume (p = 4.9 x 10^-7). This locus spans an 800-kilobase region containing RALGAPA1, with known impact on neuronal function and brain development. Aggregated rare coding variants in this gene were associated with WMHs in a previous analysis of 20,719 stroke-free and dementia-free adults.

Discussion: Our study suggests that WMH loci previously identified in NHW and AA individuals are relevant to Hispanic/Latino adults. It demonstrates the power of the diverse Hispanic/Latino population to fine-map known genetic loci and discover novel ones, augmenting our understanding of the genetic architecture of cerebral WMHs.

Background and objectives: Charcot-Marie-Tooth (CMT) disease comprises a group of inherited peripheral neuropathies caused by pathogenic variants in various genes, including ATP1A1. This gene encodes the ubiquitous α1 subunit of the sodium pump that generates the Na⁺ and K⁺ gradients that are essential for neuronal survival and excitability. We present the clinical cases of 2 unrelated patients with the same ATP1A1 variant causing dominant intermediate CMT disease and the functional characterization of the variant in the heterologous expression system.

Methods: The patients were evaluated by clinical EMG and by whole-exome sequencing. The function of sodium pump variants was studied with voltage clamp electrophysiology or using ouabain survival curves after heterologous expression in Xenopus oocytes or HEK293 cells, respectively. Localization of the variants was evaluated by fluorescence microscopy of HEK293 cells expressing fluorescently tagged sodium pumps.

Results: We describe the cases of 2 unrelated patients who presented in their second decade with a length-dependent and slowly progressive intermediate neuropathy with both axonal and demyelinating features. Whole-exome sequencing identified a de novo c.1645G>A heterozygous variant in ATP1A1 (p.Gly549Arg) in both patients. The pathogenic nature of the variant was tested through a detailed evaluation of the functional consequences of the Gly549Arg substitution using 2 heterologous expression systems and functional assays that included survival curves of transfected cells and electrophysiology. Patch clamp and 2-electrode voltage clamp electrophysiology experiments showed that the Gly549Arg variant reduced NKA function (≥50%), mainly due to a lower NKA density at the plasma membrane and, to a lesser extent, due to a reduced apparent affinity for intracellular Na⁺. The reduced plasma membrane density was also observed in HEK293 cells simultaneously expressing wildtype and Gly549Arg variants, marked with fluorescent proteins of different colors, suggesting that the mutant may be partially retained in intracellular membranes. No clear dominant-negative effects were identified in these experimental systems.

Discussion: Our results demonstrate that the pathogenic nature of this variant causes considerable loss of function due to diminished plasma membrane localization and kinetic impairments on the enzyme, without obvious dominant-negative effects. Our findings are similar to those previously reported for other CMT disease-causing ATP1A1 variants.

Background and objectives: Dystrophinopathies are X-linked recessive diseases caused by pathogenic variants in the Duchenne muscular dystrophy (DMD) gene. Some women carrying a single DMD pathogenic variant manifest variable levels of symptomatology. Those who manifest severe and early-onset symptoms are considered to be affected by dystrophinopathy rather than carriers. The aim of this study was to characterize and compare muscle structure between female DMD carriers who were asymptomatic at the time of the study and female control participants using whole-body MRI (WB-MRI) and correlate the findings with clinical and genetic data.

Methods: We conducted a cross-sectional observational study comparing a group of female carriers of DMD pathogenic variants and a group of healthy noncarrier controls. The first group included obligate and genetically confirmed DMD female carriers, not classified as having dystrophinopathy. Women in the healthy group had no family history of DMD or other muscular dystrophies. All individuals underwent WB-MRI, which was evaluated using qualitative grading scales to assess muscle edema, trophism, and fatty infiltration. Neurologic examinations, serum creatine kinase measurement, DMD genetic screening, and X-chromosome inactivation studies were performed on the DMD carriers.

Results: The study included 29 DMD female carriers and 30 healthy noncarrier controls. All DMD carriers showed signs of muscle involvement on MRI, revealing a larger proportion of skeletal muscle involvement in carriers than in controls (85% vs 27% of 48 examined muscles/group of muscles, p < 0.001). Edema, fatty infiltration, and atrophy were more common in DMD carriers (62.5% vs 8%; 81% vs 35%; and 81% vs 25%, respectively, all p < 0.001), particularly in muscles of the calves, thighs, and pelvic region. The most frequently affected muscles were gastrocnemius, gluteus maximus, and soleus. No correlations were found between the MRI results and the clinical and genetic data.

Discussion: Our findings indicate that DMD female carriers who are asymptomatic at the time of our study may be at risk of developing muscle symptoms at a future time. Multidisciplinary surveillance of DMD female carriers will facilitate early detection and management of complications.

This report presents key insights from the 2022 annual conference held in Edinburgh, commemorating the 10th anniversary of the discovery of ATP1A3 variants in alternating hemiplegia of childhood (AHC). This milestone event marked a decade of rapid advancements in research and clinical understanding, bringing together international experts and those with lived experience to reflect on progress, identify ongoing challenges, and shape the future of ATP1A3-related disease research. Over the past 10 years, our knowledge of ATP1A3-related diseases has expanded significantly, revealing a broader clinical spectrum, complex genotype-phenotype correlations, and novel pathophysiologic mechanisms. This symposium provided new data on cardiac and respiratory involvement in AHC, the impact of Na⁺, K⁺-ATPase dysfunction on neurodevelopment, and the evolving understanding of progressive disease trajectories. The conference also showcased emerging therapeutic strategies, including gene therapy, antisense oligonucleotides, and small-molecule interventions. This article synthesizes these discussions, offering a comprehensive overview of a decade of progress while highlighting the urgent need for continued collaboration. By integrating research, clinical expertise, and lived experience advocacy, the ATP1A3 community is paving the way for improved diagnosis, enhanced care, and the development of targeted treatments for these ultra-rare conditions.

Objectives: This report details a patient with a GRIA1 pathogenic variant presenting with intellectual disability (ID) and epilepsy. We describe clinical features, genetic findings, a personalized treatment approach, and a literature review of GRIA1-related disorders.

Methods: We describe clinical presentation, neuropsychological assessment, and genetic analysis. We conducted a literature review of published GRIA1-related disorders using PubMed, Simons Foundation Autism Research Initiative (SFARI) Gene, and ClinVar databases.

Results: An 8-year-old girl with ID, focal-to-bilateral tonic clonic seizure since age 5, and later atypical absences was diagnosed with a novel, de novo GRIA1 c.2530T > G, p.Leu844Val pathogenic variant. After genetic diagnosis, she was titrated to 4 mg of perampanel, an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antagonist, which led to seizure control and improvements in cognition and school performance. Literature review identified 31 patients carrying 15 different pathogenic variants. The c.1906G > A, p.Ala636Thr variant was recurrent in 17 individuals. Intellectual disability and autism spectrum disorder were common while epilepsy was reported in approximately a quarter of patients. Two patients with gain-of-function missense variants in GRIA1 and GRIA2, successfully treated with perampanel, have also been reported.

Discussion: This case emphasizes the role of targeted interventions in the management of rare genetic disorders and underscores the potential of precision medicine in addressing GRIA1-related symptoms.

Background and objectives: p.Val142Ile (p.V142I) is one of the most common pathogenic transthyretin (TTR) variants typically presents as transthyretin amyloid cardiomyopathy (ATTRv-CM), although frequent concurrent peripheral nerve involvement has been reported (94%). We aimed to characterize the polyneuropathy in p.V142I ATTR amyloidosis (ATTRv-PN) from the UK amyloidosis cohort.

Methods: We performed a retrospective cohort study of all confirmed p.V142I Variant Transthyretin Amyloidosis (ATTRv) individuals in the National Hospital for Neurology and Neurosurgery Inherited Neuropathy Clinic between January 2019 and October 2024. Because presence of ATTRv-PN was required to access disease-modifying therapy for amyloidosis during this time, all individuals with p.V142I ATTRv were evaluated for neuropathy, providing an unselected cohort.

Results: We identified 52 individuals with p.V142I ATTRv among whom the clinical presentation was cardiac in 47 (90%) and neuropathic in 5 (10%). Age at diagnosis was 71.3 ± 12.2 years. Twenty of the 52 individuals (38%) had symptoms suggestive of neuropathy with an average duration of symptoms of 4.9 ± 3.5 years 20/52 (38%) had signs suggestive of neuropathy with average Neuropathy Impairment Score being 9.0 ± 10.5. After investigations, 21/52 (40%) individuals had clinical features, neurophysiology, and/or skin biopsies consistent with ATTRv-PN (8 large-fiber/13 small-fiber). Six of the 52 individuals (12%) had neuropathies because of alternative etiologies (e.g., diabetes).

Discussion: Real-world experience from the UK national cohort of p.V142I ATTRv indicates that peripheral neuropathy is of a mild severity and less frequent than previously reported.