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The human plectin gene ( I PLEC i ) on chromosome 8q24 codes for a 4,684 amino acids large protein whose isoforms [1] are key for the functional and structural organization of filamentous cytoskeletal networks, thereby contributing to fundamental biomechanical properties of mechanical stress-bearing tissues [2]. Plectinopathies thus far comprise five autosomal-recessive entities, including epidermolysis bullosa simplex with muscular dystrophy (EBS-MD), EBS-MD with myasthenic syndrome (EBS-MD-MyS), limb girdle muscular dystrophy type 2Q, EBS with pyloric atresia, skin-only EBS and the autosomal-dominant variant EBS-Ogna [2,3]. A muscle MRI when aged 40 revealed pronounced fatty replacements of shoulder girdle muscles, the posterior compartment of thighs and the anterior compartment of his lower legs ( B Figure b 1C). [Extracted from the article]

Cerebellar atrophy (CA) is a frequent neuroimaging finding in paediatric neurology, usually associated with cerebellar ataxia. The list of genes involved in hereditary forms of CA is continuously growing and reveals its genetic complexity. We investigated ten cases with early-onset cerebellar involvement with and without ataxia by exome sequencing or by a targeted panel with 363 genes involved in ataxia or spastic paraplegia. Novel variants were investigated by in silico or experimental approaches. Seven probands carry causative variants in well-known genes associated with CA or cerebellar hypoplasia: SETX, CACNA1G, CACNA1A, CLN6 , CPLANE1 , and TBCD . The remaining three cases deserve special attention; they harbour variants in MAST1, PI4KA and CLK2 genes. MAST1 is responsible for an ultrarare condition characterised by global developmental delay and cognitive decline; our index case added ataxia to the list of concomitant associated symptoms. PIK4A is mainly related to hypomyelinating leukodystrophy; our proband presented with pure spastic paraplegia and normal intellectual capacity. Finally, in a patient who suffers from mild ataxia with oculomotor apraxia, the de novo novel CLK2 c.1120T>C variant was found. The protein expression of the mutated protein was reduced, which may indicate instability that would affect its kinase activity.

Aims: We aim to present data obtained from three patients belonging to three unrelated families with an infantile onset demyelinating neuropathy associated to somatic and neurodevelopmental delay and to describe the underlying genetic changes., Methods: We performed whole-exome sequencing on genomic DNA from the patients and their parents and reviewed the clinical, muscle and nerve data, the serial neurophysiological studies, brain and muscle MRIs, as well as the respiratory chain complex activity in the muscle of the three index patients. Computer modelling was used to characterise the new missense variant detected., Results: All three patients had a short stature, delayed motor milestone acquisition, intellectual disability and cerebellar abnormalities associated with a severe demyelinating neuropathy, with distinct morphological features. Despite the proliferation of giant mitochondria, the mitochondrial respiratory chain complex activity in skeletal muscle was normal, except in one patient in whom there was a mild decrease in complex I enzyme activity. All three patients carried the same two compound heterozygous variants of the TRMT5 (tRNA Methyltransferase 5) gene, one known pathogenic frameshift mutation [c.312_315del (p.Ile105Serfs*4)] and a second rare missense change [c.665 T > C (p.Ile222Thr)]. TRMT5 is a nuclear-encoded protein involved in the post-transcriptional maturation of mitochondrial tRNA. Computer modelling of the human TRMT5 protein structure suggests that the rare p.Ile222Thr mutation could affect the stability of tRNA binding., Conclusions: Our study expands the phenotype of mitochondrial disorders caused by TRTM5 mutations and defines a new form of recessive demyelinating peripheral neuropathy., (© 2022 The Authors. Neuropathology and Applied Neurobiology published by John Wiley & Sons Ltd on behalf of British Neuropathological Society.)

Introduction and Aims: The Charcot-Marie-Tooth Pediatric Scale (CMTPedS) is a validated and change-sensitive tool for assessing the severity of neuropathy in children and adolescents between 3 and 20 years of age. The aim of this article is to translate and validate a Spanish version of the CMTPedS in order to disseminate its use in Spanish-speaking countries., Materials and Methods: The process used to translate the CMTPedS into Spanish was the reverse parallel translation method based on the principles of good practice for translation and the cultural adaptation process of the Food and Drug Administration Guidelines. A direct translation of the original source of the CMTPedS into Spanish was performed first and reviewed by experts in Charcot-Marie-Tooth (CMT) disease trained in the use of the CMTPedS tool. The Spanish version was then translated back into English by a linguist specialised in translation., Results: The preliminary Spanish version of the CMTPedS was evaluated in 18 children with CMT aged 6-20 years (mean: 13.27). The scale was well tolerated and easy for children to understand and easy for clinicians to apply. None of the patients had any difficulty completing the scale., Conclusions: The Spanish version of the CMTPedS can be used for monitoring and conducting clinical trials in the Spanish population and in Spanish-speaking countries.

Background: Single-center clinical series provide important information on genetic distribution that can guide genetic testing. However, there are few such studies on pediatric populations with inherited peripheral neuropathies (IPNs)., Methods: Thorough genetic testing was performed on IPN patients under 20 years of age from a geographically well-defined Mediterranean area (Valencian Community, Spain), annually assessed with the Charcot-Marie-Tooth disease Pediatric Scale (CMTPedS)., Results: From 86 families with IPNs, 99 patients (59 males) were identified, 85 with sensorimotor neuropathy or CMT (2/3 demyelinating form) and 14 with distal hereditary motor neuropathy (dHMN). Genetic diagnosis was achieved in 79.5% families, with a similar mutation detection rate in the demyelinating (88.7%) and axonal (89.5%) forms, significantly higher than in the dHMN families (27.3%). CMT1A was the most common subtype, followed by those carrying heterozygous mutations in either the GDAP1 or GJB1 genes. Mutations in 15 other genes were identified, including a new pathogenic variant in the ATP1A gene. The CMTPedS detected significant disease progression in all genetic subtypes of CMT, at a rate of 1.84 (±3.7) over 1 year (p < 0.0005, n = 62) and a 2-year rate of 3.6 (±4.4: p < 0.0005, n = 45). Significant disease worsening was also detected for CMT1A over 1 (1.7 ± 3.6, p < 0.05) and 2 years (4.2 ± 4.3, p < 0.0005)., Conclusions: This study highlights the unique spectrum of IPN gene frequencies among pediatric patients in this specific geographic region, identifying the CMTPedS as a sensitive tool to detect significant disease worsening over 1 year that could help optimize the design of clinical trials., (© 2021 The Authors. Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.)

Background and Purpose: MORC2 mutations have been described as a rare cause of axonal Charcot-Marie-Tooth disease (CMT2Z). The aim of this work was to determine the frequency and distribution of these mutations throughout Spain, to provide a comprehensive phenotypical description and, if possible, to establish a genotype-phenotype correlation., Methods: Retrospectively, data on patients diagnosed with CMT2Z in Spain were collected and clinical, electrophysiological and muscle imaging information were analysed., Results: Fifteen patients with CMT2Z were identified throughout Spain, seven of them belonging to a single kindred, whilst the rest were sporadic. The most common mutation was p.R252W, and four new mutations were identified. Eleven patients were categorized as having a scapuloperoneal phenotype, with asymmetric muscle weakness, early proximal upper limb involvement and frequent spontaneous muscular activity with distal sensory impairment and pes cavus, whilst two presented with a more classic length dependent sensory motor phenotype. This distinction was corroborated by the distribution of muscle fatty infiltration in muscle imaging. Two other patients were classified as having a neurodevelopmental phenotype consisting in congenital or early onset, delay in motor milestones, and global developmental delay in one of them. Nerve conduction studies revealed an unequivocally axonal neuropathy with frequent spontaneous activity, and serum creatine kinase levels were increased in 50% of the patients., Conclusions: MORC2 mutations are a rare cause of CMT in Spain, but in-depth phenotyping reveals a recognizable phenotypic spectrum that will be clinically relevant for future identification of this disease., (© 2021 The Authors. European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.)

Background and Purpose: Distal hereditary motor neuropathies (dHMNs) are a heterogeneous group of disorders characterized by degeneration of the motor component of peripheral nerves. Currently, only 15% to 32.5% of patients with dHMN are characterized genetically. Additionally, the prevalence of these genetic disorders is not well known. Recently, biallelic mutations in the sorbitol dehydrogenase gene (SORD) have been identified as a cause of dHMN, with an estimated frequency in undiagnosed cases of up to 10%., Methods: In the present study, we included 163 patients belonging to 108 different families who were diagnosed with a dHMN and who underwent a thorough genetic screening that included next-generation sequencing and subsequent Sanger sequencing of SORD., Results: Most probands were sporadic cases (62.3%), and the most frequent age of onset of symptoms was 2 to 10 years (28.8%). A genetic diagnosis was achieved in 37/108 (34.2%) families and 78/163 (47.8%) of all patients. The most frequent cause of distal hereditary motor neuropathies were mutations in HSPB1 (10.4%), GARS1 (9.8%), BICD2 (8.0%), and DNAJB2 (6.7%) genes. In addition, 3.1% of patients were found to be carriers of biallelic mutations in SORD. Mutations in another seven genes were also identified, although they were much less frequent. Eight new pathogenic mutations were detected, and 17 patients without a definite genetic diagnosis carried variants of uncertain significance. The calculated minimum prevalence of dHMN was 2.3 per 100,000 individuals., Conclusions: This study confirms the genetic heterogeneity of dHMN and that biallelic SORD mutations are a cause of dHMN in different populations., (© 2020 European Academy of Neurology.)

It has been suggested that aberrant activation of glycogen synthase kinase-3-beta (GSK-3β) can trigger abnormal tau hyperphosphorylation and aggregation, which ultimately leads to neuronal/synaptic damage and impaired cognition in Alzheimer disease (AD). We examined if isoform-selective partial reduction of GSK-3β can decrease pathological tau changes, including hyperphosphorylation, aggregation, and spreading, in mice with localized human wild-type tau (hTau) expression in the brain. We used adeno-associated viruses (AAVs) to express hTau locally in the entorhinal cortex of wild-type and GSK-3β hemi-knockout (GSK-3β-HK) mice. GSK-3β-HK mice had significantly less accumulation of hyperphosphorylated tau in synapses and showed a significant decrease of tau protein spread between neurons. In primary neuronal cultures from GSK-3β-HK mice, the aggregation of exogenous FTD-mutant tau was also significantly reduced. These results show that a partial decrease of GSK-3β significantly represses tau-initiated neurodegenerative changes in the brain, and therefore is a promising therapeutic target for AD and other tauopathies., Competing Interests: Teresa Gómez-Isla participated as speaker in an Eli Lilly and Company-sponsored educational symposium and serves in an Eli Lilly Data Monitoring Committee. All other authors declare no competing interests., (© 2021 The Authors.)

Objective: To analyze those factors contributing to the diagnostic delay in ALS. Methods: Consecutive ALS patients were categorized as those studied in departmental hospitals and those studied in a referral ALS center. Demographic and clinical variables, together with data of the diagnostic pathway were collected. Multivariable models were used to assess their effect in the time between symptoms onset and the first neurologist visit (time symptoms-neurologist), in the time between the first neurologist visit and the diagnosis (time neurologist-diagnosis) and in the diagnostic delay. Results: 166 ALS patients with a median diagnostic delay of 11.53 months (IQR: 6.68, 15.23) were included. The median diagnostic delay was 8.57 months (5.16, 11.61) in the referral center vs. 12.08 months (6.87, 16.8) in departmental centers. Bulbar onset, fast progression rate, upper motor neuron predominant phenotype and an early referral to the neurologist were associated with a shorter time between symptoms-neurologist. Being studied in a referral center was associated with a shorter time between neurologist-diagnosis. Comorbidities, familial ALS, bulbar onset, early referral to the neurologist and being studied in a referral center were associated with a shorter diagnostic delay. For patients studied in departmental hospitals, fast progression rate was also strongly associated with a shorter time between neurologist-diagnosis and diagnostic delay. Conclusion: Unmodifiable factors (comorbidities, familial ALS, bulbar onset, and progression rate) as well as modifiable factors (early referral to the neurologist and the evaluation in an ALS referral center) have an independent effect in the diagnostic delay. The universalization of ALS Units is probably the most efficient measure to reduce the diagnostic delay., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Martínez-Molina, Argente-Escrig, Polo, Hervás, Frasquet, Cortés, Sevilla and Vázquez-Costa.)

Background: Mutations in the FGD4 gene cause an autosomal recessive demyelinating peripheral neuropathy referred to as CMT4H, characterized by its onset in infancy or early-childhood and its slow progression., Methods: The clinical and genetic status of two patients with CMT4H was studied, performing genetic testing with a panel of genes and analysing FGD4 mRNA expression by quantitative PCR., Results: Two novel FGD4 variants (c.514delG and c.2211dupA) were identified in two mildly affected Spanish siblings with CMT4H, and with disease onset in late adolescence/adulthood (one of them remaining asymptomatic at 20). On examination, foot deformity was observed without weakness or sensory involvement, and in the muscles of the lower extremities magnetic resonance imaging showed no fat replacement. Further analysis of FGD4 expression in peripheral blood suggested that neither mutation affected splicing, nor did they affect the dosage of FGD4 mRNA (compared to a healthy control). It was predicted that each allele would produce a truncated protein, p.Ala172Glnfs*28 (c.514delG) and p.Ala738Serfs*5 (c.2211dupA), the latter containing all the functional domains of the native protein., Conclusions: The conservation of functional domains in the proteins produced from the FGD4 gene of two patients with CMT4H, could explain both the milder phenotype and the later disease onset in these patients. These results expand the clinical and mutational spectrum of FGD4-related peripheral neuropathies., (Copyright © 2019. Published by Elsevier B.V.)

Background: Acquired periodic alternating nystagmus (PAN) is a rare but well-defined syndrome that consists of a horizontal nystagmus that cyclically reverses its direction. PAN can be caused by degenerative, neoplastic, or toxic diseases of the cerebellum and, in a few cases, by subacute cerebellar ataxia of immune origin., Case Presentation: A 44-year-old man came to our attention because of rapidly progressive gait instability and blurred vision. Clinical examination showed PAN and a mild pancerebellar syndrome. Eye movement recordings disclosed a short cycle PAN with significant slow-phase velocity only in darkness. Under the effect of a γ-aminobutyric acid type B (GABA B ) agonist, PAN was not modified. Right after treatment with intravenous immunoglobulin (IVIg) was started, PAN was essentially eliminated. Three months after last dose of IVIg, this nystagmus reappeared., Conclusions: IVIg resolved PAN in this patient. This finding may point to an autoimmune mechanism underlying this patient's nystagmus. This case suggests that the usefulness of IVIg at treating PAN might be worth a consideration in similar clinical settings.

Objective: Velocity storage mechanism is a multisensory rotation estimator; it compensates for errors in the information provided by the peripheral vestibular organs by means of an adjustment in the duration of the vestibular signal. The aim of this study was to determine the activity of the velocity storage mechanism in the presence of a labyrinthine disorder, using galvanic vestibular stimulation to cause direct activation of the vestibular afferent neurons., Materials and Methods: Forty-one subjects with definite Meniere's disease (MD) and 36 healthy volunteers were evaluated using a 20-s galvanic vestibular stimulation., Results: We found a post-stimulus nystagmus overshoot exclusively in subjects with MD (47% in subjects with unilateral disease and 82% in subjects with bilateral disease), but no overshoot in healthy subjects., Conclusion: Because post-stimulus nystagmus overshoot is caused by the velocity storage mechanism, this finding suggests an increase in the velocity storage in subjects with a labyrinthine disease.