Diagnosis, natural history, and management of Charcot–Marie–Tooth disease

Validity of Cardiopulmonary Exercise Testing for Assessing Aerobic Capacity in Neuromuscular Diseases

OBJECTIVES

To determine the content validity of cardiopulmonary exercise testing (CPET) for assessing peak oxygen uptake (VO2peak) in neuromuscular diseases (NMD).

DESIGN

Baseline assessment of a randomized controlled trial.

SETTING

Academic hospital.

PARTICIPANTS

Eighty-six adults (age: 58.0±13.9 y) with Charcot-Marie-Tooth disease (n=35), postpolio syndrome (n=26), or other NMD (n=25).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

Workload, gas exchange variables, heart rate, and ratings of perceived exertion were measured during CPET on a cycle ergometer, supervised by an experienced trained assessor. Muscle strength of the knee extensors was assessed isometrically with a fixed dynamometer. Criteria for confirming maximal cardiorespiratory effort during CPET were established during 3 consensus meetings of an expert group. The percentage of participants meeting these criteria was assessed to quantify content validity.

RESULTS

The following criteria were established for maximal cardiorespiratory effort: a plateau in oxygen uptake (VO2plateau) as the primary criterion, or 2 of 3 secondary criteria: (1) peak respiratory exchange ratio (RERpeak) ≥1.10 (2), peak heart rate ≥85% of predicted maximal heart rate; and (3) peak rating of perceived exertion (RPEpeak) ≥17 on the 6-20 Borg scale. These criteria were attained by 71 participants (83%). VO2plateau, RERpeak ≥1.10, peak heart rate ≥85%, and RPEpeak ≥17 were attained by 31%, 73%, 69%, and 72% of the participants, respectively. Peak workload, VO2peak, and knee extension muscle strength were significantly higher, and body mass index was lower (all P<.05), in participants with maximal cardiorespiratory effort than other participants.

CONCLUSIONS

Most people with NMD achieved maximal cardiorespiratory effort during CPET. This study provides high quality evidence of sufficient content validity of VO2peak as a maximal aerobic capacity measure. Content validity may be lower in more severely affected people with lower physical fitness.

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.

Is there a place for dorsal hemiepiphysiodesis of the first metatarsal in the treatment of pes cavovarus?

The objective of this study is to describe and evaluate dorsal hemiepiphysodesis of the first metatarsal as an osteotomy replacement technique. Retrospective analysis of patients with pes cavovarus (PCV) treated in our center with dorsal hemiepiphysodesis of the first metatarsal. Meary's angle, calcaneal pitch, and Moreau Costa Bartani were compared pre and post-operatively and the ratio between width and foot length was monitored. Between May 2012 and May 2022, eight patients (14 feet) with PCV underwent dorsal hemiepiphysiodesis of the first metatarsal combined with the Steindler procedure. Four patients (50%) were male. The average age for boys at surgery was 10.75 years (10-11) and for girls was 9.75 years (8-11). Most patients (87.5%) had idiopathic PCV and 12.5% had a neurological PCV. Median follow-up was 4.3 years (1.5-10) and a benefit was seen in all patients in Moreau Costa Bartani angle (112.64° vs. 120.59°; P value = 0.003), calcaneal pitch (26.48° vs. 25.36°; P value = 0.091) and Meary's angle (10.60° vs. 5.36°; P value = 0.008) after surgery. Supination improvement was also shown (0.21 vs. 0.24; P value = 0.039). Despite the limited number of patients, the results demonstrated that dorsal hemiepiphysiodesis of the first metatarsal can be a valid alternative to osteotomy of the base of the first metatarsal, with less morbidity and a gradual and dynamic correction throughout growth.

Current Treatment Methods for Charcot-Marie-Tooth Diseases

Charcot-Marie-Tooth (CMT) disease, the most common inherited neuromuscular disorder, exhibits a wide phenotypic range, genetic heterogeneity, and a variable disease course. The diverse molecular genetic mechanisms of CMT were discovered over the past three decades with the development of molecular biology and gene sequencing technologies. These methods have brought new options for CMT reclassification and led to an exciting era of treatment target discovery for this incurable disease. Currently, there are no approved disease management methods that can fully cure patients with CMT, and rehabilitation, orthotics, and surgery are the only available treatments to ameliorate symptoms. Considerable research attention has been given to disease-modifying therapies, including gene silencing, gene addition, and gene editing, but most treatments that reach clinical trials are drug treatments, while currently, only gene therapies for CMT2S have reached the clinical trial stage. In this review, we highlight the pathogenic mechanisms and therapeutic investigations of different subtypes of CMT, and promising therapeutic approaches are also discussed.

Efficient data labeling strategies for automated muscle segmentation in lower leg MRIs of Charcot-Marie-Tooth disease patients

We aimed to develop efficient data labeling strategies for ground truth segmentation in lower-leg magnetic resonance imaging (MRI) of patients with Charcot-Marie-Tooth disease (CMT) and to develop an automated muscle segmentation model using different labeling approaches. The impact of using unlabeled data on model performance was further examined. Using axial T1-weighted MRIs of 120 patients with CMT (60 each with mild and severe intramuscular fat infiltration), we compared the performance of segmentation models obtained using several different labeling strategies. The effect of leveraging unlabeled data on segmentation performance was evaluated by comparing the performances of few-supervised, semi-supervised (mean teacher model), and fully-supervised learning models. We employed a 2D U-Net architecture and assessed its performance by comparing the average Dice coefficients (ADC) using paired t-tests with Bonferroni correction. Among few-supervised models utilizing 10% labeled data, labeling three slices (the uppermost, central, and lowermost slices) per subject exhibited a significantly higher ADC (90.84±3.46%) compared with other strategies using a single image slice per subject (uppermost, 87.79±4.41%; central, 89.42±4.07%; lowermost, 89.29±4.71%, p < 0.0001) or all slices per subject (85.97±9.82%, p < 0.0001). Moreover, semi-supervised learning significantly enhanced the segmentation performance. The semi-supervised model using the three-slices strategy showed the highest segmentation performance (91.03±3.67%) among 10% labeled set models. Fully-supervised model showed an ADC of 91.39±3.76. A three-slice-based labeling strategy for ground truth segmentation is the most efficient method for developing automated muscle segmentation models of CMT lower leg MRI. Additionally, semi-supervised learning with unlabeled data significantly enhances segmentation performance.

Noninvasive ventilation and laser-assisted unilateral posterior cordotomy as novel multidisciplinary approaches for Charcot-Marie-Tooth disease 4B vocal cord paralysis: a case report

BACKGROUND

Charcot-Marie-Tooth disease (CMT) is one of the most common inherited neuropathies. The disease is generally characterized by sensory loss most prominent in distal extremities, muscle weakness, and muscle wasting. There is still no effective therapy for Charcot-Marie-Tooth disease.

CASE PRESENTATION

The patient is a 6-year-old Iranian girl, of Fars ethnicity, who was admitted with a chief complaint of hoarseness and an impression of Charcot-Marie-Tooth disease type 4B. She was initially treated with noninvasive ventilation and, after a year, electively underwent cordotomy as a novel therapeutic approach.

CONCLUSIONS

Charcot-Marie-Tooth disease type 4B is a less common but important cause of stridor. Noninvasive ventilation treatment and unilateral posterior cordotomy can be utilized for hereditary neuropathies.

Charcot-Marie-Tooth Disease and Hearing Loss: A Systematic Review With Meta-Analysis

OBJECTIVE

To characterize the pattern of hearing loss in Charcot-Marie-Tooth (CMT) disease to help guide clinical management.

DATABASES REVIEWED

CINAHL, PubMed, and Scopus.

METHODS

Two independent investigators selected studies on CMT patients with pure-tone average (PTA) and auditory brainstem response (ABR) data. Case reports, case series <5 patients, and data that overlapped with another study were excluded. Investigators performed data extraction, quality rating, and risk-of-bias assessment using the Newcastle-Ottawa Scale. Meta-analysis of mean difference using fixed/random effects models was used. Also, data were analyzed using a weighted one-way analysis of variance, with post-hoc Tukey's test for comparison.

RESULTS

Ultimately, 6 prospective studies (N = 197) were included. The most common demyelinating subtype (CMT1A) had significantly prolonged ABR latency values across wave III (0.20 ms, 95% confidence interval [CI]: 0.05-0.35), wave V (0.20 ms, 95% CI: 0.01-0.39), waves I-III (0.20 ms, 95% CI: 0.01-0.39), and waves I-V (0.20 ms, 95% CI: 0.01-0.39) when compared to matched controls. The autosomal recessive demyelinating subtype (CMT4C) had significantly worse PTA when compared to the most common subtype (CMT1A) (Δ 28.93 dB, 95% CI 18.34-39.52) and nondemyelinating subtype (CMT2A) (Δ 28.3 dB, 95% CI: 15.98-40.62).

CONCLUSIONS

Patients with CMT can present with a variety of phenotypes depending on the causative mutation. The ABR interpeak latency values for the most common demyelinating form of CMT are delayed when compared to matched controls. Most subtypes have normal hearing thresholds, apart from CMT4C, which presents with mild hearing loss on average.

Jean-Martin Charcot: Pioneer of Neurology

Jean-Martin Charcot, born on November 29, 1825, in Paris, France, is known as the father of neurology. During a time when neurology was not yet a recognized medical specialty, Charcot's pioneering contributions significantly advanced the field. Charcot's use of the anatomo-clinical method, which correlates clinical symptoms with anatomical findings, led to the discovery and characterization of numerous neurological conditions, including multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Charcot's joint, and Charcot-Marie-Tooth (CMT) disease. His methodical approach to documenting clinical signs and conducting post-mortem examinations revolutionized neurological research and diagnosis, laying the groundwork for modern neurology. The anatomo-clinical methods continue to be a vital tool in neurological research and practice today. Charcot's work extended beyond clinical practice, influencing the study of neurology through his role as an educator and mentor to many, including Sigmund Freud. Despite some controversies and a reputation for being difficult to work with, Charcot's legacy endures, with his initial discoveries fostering greater awareness and the development of therapies for various neurological disorders.

Cochlear implantation in patients with Charcot-Marie-Tooth disease: two cases with a review of the literature

PURPOSE

To report two cases of bilateral cochlear implantation (CI) in Charcot-Marie-Tooth disease (CMT) patients with novel mutations. Furthermore, we conducted a detailed literature review on the profile and outcomes of CI in this uncommon clinical circumstance.

CASE PRESENTATION

Case 1 involved a 25-year-old woman who was referred for sudden hearing loss (HL) in her left ear and had a 7-year history of HL in her right ear. She was diagnosed with CMT type 1 with a thymidine phosphorylase gene mutation. CI was performed on her left side because her hearing gradually worsened to deafness in both ears. At 3 months post-operation, her speech discrimination score without lip-reading improved from 0 to 100%. She underwent a second CI on her right ear 6 months after her first CI. Two years from her first operation, the speech discrimination score was 100%. Case 2 received her first CI on her right ear at the age of nine for her bilateral HL. She was diagnosed with CMT type 2 with a Twinkle mitochondrial DNA helicase gene mutation. Preoperatively, the speech discrimination score in both ear-aided conditions was 70%. At the 7-year post-operation follow-up, the speech discrimination score was 76%. A second CI was performed due to decreasing hearing ability in her left ear. The speech discrimination score showed 100% at 7 months after the second CI.

CONCLUSIONS

CI is an effective hearing rehabilitation option for CMT patients with severe-to-profound SNHL. Neuro-otologists should consider CI as a treatment option, even though hearing loss in CMT is associated with auditory neuropathy spectrum disease (ANSD).

Pharmacological Doses of Thiamine Benefit Patients with the Charcot-Marie-Tooth Neuropathy by Changing Thiamine Diphosphate Levels and Affecting Regulation of Thiamine-Dependent Enzymes

Charcot-Marie-Tooth (CMT) neuropathy is a polygenic disorder of peripheral nerves with no effective cure. Thiamine (vitamin B1) is a neurotropic compound that improves neuropathies. Our pilot study characterizes therapeutic potential of daily oral administration of thiamine (100 mg) in CMT neuropathy and its molecular mechanisms. The patient hand grip strength was determined before and after thiamine administration along with the blood levels of the thiamine coenzyme form (thiamine diphosphate, ThDP), activities of endogenous holo-transketolase (without ThDP in the assay medium) and total transketolase (with ThDP in the assay medium), and transketolase activation by ThDP [1 - (holo-transketolase/total transketolase),%], corresponding to the fraction of ThDP-free apo-transketolase. Single cases of administration of sulbutiamine (200 mg) or benfotiamine (150 mg) reveal their effects on the assayed parameters within those of thiamine. Administration of thiamine or its pharmacological forms increased the hand grip strength in the CMT patients. Comparison of the thiamin status in patients with different forms of CMT disease to that of control subjects without diagnosed pathologies revealed no significant differences in the average levels of ThDP, holo-transketolase, or relative content of holo and apo forms of transketolase. However, the regulation of transketolase by thiamine/ThDP differed in the control and CMT groups: in the assay, ThDP activated transketolase from the control individuals, but not from CMT patients. Thiamine administration paradoxically decreased endogenous holo-transketolase in CMT patients; this effect was not observed in the control group. Correlation analysis revealed sex-specific differences in the relationship between the parameters of thiamine status in both the control subjects and patients with the CMT disease. Thus, our findings link physiological benefits of thiamine administration in CMT patients to changes in their thiamine status, in particular, the blood levels of ThDP and transketolase regulation.

Diagnostic value of lower extremity ultrasonographic nerve enlargement for differentiating demyelinating Charcot-Marie-Tooth disease from chronic inflammatory demyelinating polyneuropathy

BACKGROUND AND PURPOSE

We previously reported that nerve enlargement assessment by nerve ultrasonography of the intermediate upper limb is applicable for distinguishing demyelinating Charcot-Marie-Tooth disease (CMT) from chronic inflammatory demyelinating polyneuropathy (CIDP). However, differences in the severity and distribution patterns of lower extremity nerve enlargement have not been established for either disease. Therefore, we examined the utility of lower extremity nerve ultrasonography for differentiating between CMT and CIDP.

METHODS

Twelve patients with demyelinating CMT and 17 patients with CIDP were evaluated. The median, ulnar, tibial, and fibular nerves were evaluated in three regions: the distal upper extremity, intermediate upper extremity, and lower extremity. Of the 14 selected screening sites, the number of sites that exhibited nerve enlargement (enlargement site number, ESN) in each region was determined.

RESULTS

The screening ESNs in the intermediate region and lower extremities were greater in patients with demyelinating CMT than in patients with CIDP and greater than the ESN in the distal region (p = 0.010, p = 0.001, and p = 0.101, respectively). The ESNs in the intermediate region and lower extremities significantly differed among patients with typical CIDP, CIDP variants, and demyelinating CMT (p = 0.084 and p < 0.001). Among the 14 selected screening sites, the combined upper and lower extremity ESNs exhibited the highest AUC (0.92; p < 0.001).

CONCLUSIONS

Combining the upper and lower extremities for ultrasonographic nerve measurement more accurately distinguishes CIDP from demyelinating CMT.

Telecoaching: a potential new training model for Charcot-Marie-Tooth patients: a systematic review

Introduction

Charcot-Marie-Tooth disease (CMT) is an inherited neuropathy that affects the sensory and motor nerves. It can be considered the most common neuromuscular disease, with a prevalence of 1/2500.

Methods

Considering the absence of a specific medical treatment and the benefits shown by physical activity in this population, a systematic review was completed using several search engines (Scopus, PubMed, and Web of Science) to analyze the use, effectiveness, and safety of a training program performed in telecoaching (TC). TC is a new training mode that uses mobile devices and digital technology to ensure remote access to training.

Results

Of the 382 studies identified, only 7 met the inclusion criteria. The effects of a TC training program included improvements in strength, cardiovascular ability, and functional abilities, as well as gait and fatigue. However, the quality of the studies was moderate, the size of the participants in each study was small, and the outcome measured was partial.

Discussion

Although many studies have identified statistically significant changes following the administration of the TC training protocol, further studies are needed, with appropriate study power, better quality, and a higher sample size.

Bilateral hearing impairment as an early symptom in a patient with Charcot-Marie-Tooth Type 1: the first case report from Syria

Introduction

Charcot-Marie-Tooth (CMT) is a group of inherited neuromuscular disorders that vary clinically and genetically. It is characterized by peripheral nerve damage, leading to muscle weakness and sensory loss.

Case presentation

A 13-year-old male presented to the rheumatology department with bilateral hearing impairment since the age of 3 years, pes cavus, and difficulties walking. Some family members had Achilles tendon lengthening surgery. During physical examination, the patient had a shortened Achilles tendon, there are high arches in the feet, curled toes, loss of touch sensation in the feet, ankles, and legs, atrophy in the foot muscles. An eye examination revealed a discrepancy that needed glasses. Neurological findings included horizontal and vertical nystagmus, proprioception disorder, and demyelinating sensorimotor disorder diagnosed as CMT type 1. The audiogram showed bilateral sensorineural hearing impairment. MRI revealed spinal disc bulges. The treatment plan includes Achilles tendon lengthening surgery and physical therapy.

Clinical discussion

CMT patients need to receive supportive treatment including physical therapy, hearing aids, and glasses, to help improve their quality of life.

Conclusion

CMT disease is a genetic disorder that causes difficulties in movement, coordination, and daily activities due to muscle weakness and sensory impairments. In a few cases, patients have been documented to have bilateral hearing impairment as their first symptoms. It affects individuals in Syria and around the world, and requires proper diagnosis and treatment.

Upper and lower limb tremor in Charcot-Marie-Tooth neuropathy type 1A and the implications for standing balance

BACKGROUND

Neuropathic tremor occurs in Charcot-Marie-Tooth neuropathy type 1A (CMT1A; hereditary motor and sensory neuropathy, HMSN), although the pathophysiological mechanisms remain to be elucidated. Separately, lower limb tremor has not been explored in CMT1A and could be associated with imbalance as in other neuropathies. The present study aimed to determine tremor characteristics in the upper and lower limbs in CMT1A and relate these findings to clinical disability, particularly imbalance.

METHODS

Tremor and posturography studies were undertaken in phenotyped and genotyped CMT1A patients. Participants underwent detailed clinical assessment, tremor study recordings, and nerve conduction studies. Tremor stability index was calculated for upper limb tremor and compared to essential tremor.

RESULTS

Seventeen patients were enrolled. Postural and kinetic upper limb tremors were evident in 65%, while postural and orthostatic lower limb tremors were seen in 35% of CMT1A patients. Peak upper limb frequencies were lower distally (~ 6 Hz) and higher proximally (~ 9 Hz), were unchanged by weight-loading, and not impacted by fatigue. The tremor stability index was significantly higher in CMT1A than in essential tremor. A 5-6 Hz lower limb tremor was recorded which did not vary along the limb and was unaffected by fatigue. Balance was impaired in patients with postural lower limb tremor. A high frequency peak on posturography was associated with 'good' balance.

CONCLUSIONS

Tremor is a common clinical feature in CMT1A, distinct from essential tremor, mediated by a complex interaction between peripheral and central mechanisms. Postural lower limb tremor is associated with imbalance; strategies aimed at tremor modulation could be of therapeutic utility.

Targeting PI3K/Akt/mTOR signaling in rodent models of PMP22 gene-dosage diseases

Haplo-insufficiency of the gene encoding the myelin protein PMP22 leads to focal myelin overgrowth in the peripheral nervous system and hereditary neuropathy with liability to pressure palsies (HNPP). Conversely, duplication of PMP22 causes Charcot-Marie-Tooth disease type 1A (CMT1A), characterized by hypomyelination of medium to large caliber axons. The molecular mechanisms of abnormal myelin growth regulation by PMP22 have remained obscure. Here, we show in rodent models of HNPP and CMT1A that the PI3K/Akt/mTOR-pathway inhibiting phosphatase PTEN is correlated in abundance with PMP22 in peripheral nerves, without evidence for direct protein interactions. Indeed, treating DRG neuron/Schwann cell co-cultures from HNPP mice with PI3K/Akt/mTOR pathway inhibitors reduced focal hypermyelination. When we treated HNPP mice in vivo with the mTOR inhibitor Rapamycin, motor functions were improved, compound muscle amplitudes were increased and pathological tomacula in sciatic nerves were reduced. In contrast, we found Schwann cell dedifferentiation in CMT1A uncoupled from PI3K/Akt/mTOR, leaving partial PTEN ablation insufficient for disease amelioration. For HNPP, the development of PI3K/Akt/mTOR pathway inhibitors may be considered as the first treatment option for pressure palsies.

Differences in respiratory function, depressive symptoms and quality of life between patients with hereditary motor and sensory neuropathy and myotonic dystrophy undergoing maintenance rehabilitation

Hereditary motor and sensory neuropathy (HMSN) and myotonic dystrophy (MD) are chronic neuromuscular diseases that cause progressive muscular impairment and impact patient's quality of life. Conflicting findings in existing literature underscore the need for focussed research on specific health aspects in these patients. The aim of the study was to explore the differences in respiratory function, depressive symptoms and quality of life between patients with HMSN and MD undergoing maintenance rehabilitation. Our prospective observational study included 62 HMSN patients (median age 53.5, range 19-79 years; 38 women) and 50 MD patients (median age 54.0, range 18-77 years; 34 women) undergoing maintenance rehabilitation. They performed respiratory function tests (vital capacity, forced vital capacity, forced expiratory volume and peak expiratory flow) and respiratory muscle strength tests (maximum inspiratory pressure, maximum expiratory pressure and sniff nasal inspiratory force). The Center for Epidemiological Studies-Depression Scale was used to evaluate depression, and their health-related quality of life was assessed using the Quality of Life in Genetic Neuromuscular Disease Questionnaire. Using logistic regression, we examined group-difference in presence of depressive symptoms while accounting for age, symptoms duration, and marital status. Multiple linear regression was used to assess the difference in quality-of-life scores, adjusting for age, gender, and symptoms' duration. The HMSN group achieved statistically significantly better results than the MD group on all respiratory measures (about 17% absolute difference in the respiratory function measures and 30% relative difference in the respiratory muscle strength measures on average). Both groups exhibited a high level of depression symptoms (HMSN 24%, MD 44%; estimated adjusted odds-ratio MD vs. HMSN 1.9, 95% CI 0.8-4.5, P  = 0.127). We did not find a statistically significant difference between the groups regarding quality-of-life domains, though a trend towards better quality-of-life among the HMSN patients could be observed. The implication for future practice is that the MD patients would potentially benefit the most from targeted respiratory-rehabilitation interventions, and both groups could benefit from focussed mental-health interventions.

Autoimmune Autonomic Neuropathy: From Pathogenesis to Diagnosis

Autoimmune autonomic ganglionopathy (AAG) is a disease of autonomic failure caused by ganglionic acetylcholine receptor (gAChR) autoantibodies. Although the detection of autoantibodies is important for distinguishing the disease from other neuropathies that present with autonomic dysfunction, other factors are important for accurate diagnosis. Here, we provide a comprehensive review of the clinical features of AAG, highlighting differences in clinical course, clinical presentation, and laboratory findings from other neuropathies presenting with autonomic symptoms. The first step in diagnosing AAG is careful history taking, which should reveal whether the mode of onset is acute or chronic, followed by an examination of the time course of disease progression, including the presentation of autonomic and extra-autonomic symptoms. AAG is a neuropathy that should be differentiated from other neuropathies when the patient presents with autonomic dysfunction. Immune-mediated neuropathies, such as acute autonomic sensory neuropathy, are sometimes difficult to differentiate, and therefore, differences in clinical and laboratory findings should be well understood. Other non-neuropathic conditions, such as postural orthostatic tachycardia syndrome, chronic fatigue syndrome, and long COVID, also present with symptoms similar to those of AAG. Although often challenging, efforts should be made to differentiate among the disease candidates.

Quantified fat fraction as biomarker assessing disease severity in rare Charcot-Marie-Tooth subtypes

Objective

Charcot-Marie-Tooth (CMT) disease is the most common inherited neuromuscular disorder. Multi-echo Dixon MRI technique is a highly sensitive method for quantifying muscle fatty infiltration, which may provide excellent value for the assessment of CMT. Due to the rareness of the disease, its use in CMT disease has been rarely evaluated, especially in subtypes.

Methods

Thirty-four CMT1 patients, 25 CMT2 patients, and 10 healthy controls were recruited. All of the recruited CMT1 patients are CMT1A with PMP22 duplication. Among CMT2 patients, 7 patients are CMT2A with MFN2 mutation, and 7 patients have SORD mutations. Multi-echo Dixon MRI imaging was performed. The fat fractions (FFs) of 5 muscle compartments of the leg were measured at proximal, middle, and distal levels by two specialized musculoskeletal radiologists. Comparisons between CMT1, CMT2, and genetically defined subtypes were conducted.

Results

A proximal-distal gradient (27.6 ± 15.9, 29.9 ± 19.7, and 40.5 ± 21.4, p = 0.015) with a peroneal predominance (p = 0.001) in fat distribution was observed in CMT1. Significant differences in the soleus muscle FFs at proximal (19.1 ± 14.7 vs. 34.8 ± 25.1, p = 0.034) and medial levels (23.5 ± 21 vs. 38.0 ± 25.6, p = 0.044) were observed between CMT1 and CMT2 patients. Between PMP2 duplication and MFN2 mutation group, a significant difference in the soleus muscle FF was also observed (23.5 ± 21.0 vs. 54.7 ± 20.2, p = 0.039). Prominent correlations of calf muscle FFs with functional scores were observed.

Discussion

Multi-echo Dixon MRI imaging is a valuable tool for assessing disease severity in CMT. The difference in patterns of fatty infiltration of CMT subtypes is first reported, which could provide references when making targeted training plans.

Short-term effects of foot surgery on walking-related pain, function, and satisfaction in patients with Charcot-Marie-Tooth disease: a prospective cohort study

Introduction

Patients with Charcot-Marie-Tooth disease (CMT) often suffer from walking-related pain (WRP), muscle weakness, foot deformities, and reduced ankle dorsiflexion (DF), which affects their ability to walk and daily activities. Functional surgery (FS) can restore foot deviations, affecting the loading ability during gait. We assessed the short-term effects of FS in patients with CMT on WRP, foot and ankle structure, and function, along with patients' perceived improvement.

Methods

This is a prospective cohort study on CMT patients who had undergone FS and rehabilitation. We analyzed the changes after 1 month, focusing on WRP, DF, the center of pressure progression (COPP) during walking, and measures of walking ability. The non-parametric Wilcoxon test was used.

Results

Ten patients were included. One month after FS, WRP reduced from 5.5 (IQR = 3.5) to 2 (IQR = 3.5), p = 0.063, with an effect size of 0.615. The highest decrease was found in patients with very high pre-surgical pain levels. DF almost reached 10° for both active and passive movements (p < 0.05), and COPP improved from 44 to 60% (p = 0.009) of foot length. Gait speed, lower limb functioning, and balance did not change. More than half of the sample felt improved or much improved after FS.

Conclusion

FS can be effective in reducing WRP and restoring foot posture in CMT patients in the short-term, which allows them to wear shoes, and leads to a perceived improvement and satisfaction. Lack of improvement in functional skills may be due to muscle weakness typical of CMT. Studies with longer follow-ups may confirm these hypotheses.

Physical Activity in Patients with Neuromuscular Disease Three Years after COVID-19, a Longitudinal Survey: The After-Effects of the Quarantine and the Benefits of a Return to a Healthier Life-Style

BACKGROUND

Quarantine was one of the strategies adopted by governments against the spread of COVID-19. This restriction has caused an increase in sedentary behaviors and a decrease in the practice of physical activity (PA), with a consequent negative impact on lifestyle both in healthy people and in those who need constant practice of PA to combat diseases, such as patients suffering from neuromuscular diseases (NMDs). Hence, this study aimed to compare PA levels among patients with NMD during and after quarantine.

METHODS

An adapted version of the International Physical Activity Questionnaire Short-Form and the Short-Form Health Survey were administered during COVID-19 quarantine (T0) and after 3 years (T1) to 91 Italian patients with NMDs.

RESULTS

We found a significant increase in the total PA level at T1, with no significant changes in vigorous-intensity PA. Moreover, a significant decrease in the PA level was found among the patients with different NMDs. No significant changes in physical component scores and mental component scores were detected.

CONCLUSIONS

Our results suggest that it would be necessary to provide alternative indoor exercise settings to prevent the adoption of sedentary behaviors.

A Novel Mutation in Frabin (FGD4) Causing a Mild Phenotype of CMT4H in an Indian Patient

Charcot-Marie-Tooth disease 4H(CMT4H) is an autosomal recessive demyelinating form of CMT caused by FGD4/FRABIN mutations. CMT4H is characterized by early onset and slowly progressing motor and sensory deficits in the distal extremities, along with foot deformities. We describe a patient with CMT4H who presented with rapidly progressing flaccid quadriparesis during the postpartum period, which improved significantly with steroid therapy. Magnetic resonance imaging and ultrasonography demonstrated considerable nerve thickening with increased cross-sectional area in the peripheral nerves. A nerve biopsy revealed significant demyelination and myelin outfolding. This is the first report of an Indian patient with a novel homozygous nonsense c.1672C>T (p.Arg558Ter) mutation in the FGD4 gene, expanding the mutational and phenotypic spectrum of this disease.

Effects of intensive rehabilitation on functioning in patients with mild and moderate Charcot-Marie-Tooth disease: a real-practice retrospective study

Charcot-Marie-Tooth (CMT) disease is one of the most common inherited neuropathies and can lead to progressive muscular weakness, pes cavus, loss of deep tendon reflexes, distal sensory loss, and gait impairment. There are still no effective drugs or surgical therapies for CMT, and supportive treatment is limited to rehabilitative therapy and surgical treatment of skeletal deformities. Many rehabilitative therapeutic approaches have been proposed, but timing and cadence of rehabilitative intervention are not clearly defined, and long-term follow-up is lacking in literature. The aim of this real-practice retrospective study was to assess the effectiveness of an intensive neurorehabilitation protocol on muscle strength and functioning in CMT patients. We analyzed data of patients with diagnosis of mild to moderate CMT. The rehabilitation program lasted 2-4 h a day, 5 days a week, for 3 weeks and consisted of manual treatments, strengthening exercises, stretching, core stability, balance and resistance training, aerobic exercises, and tailored self-care training. Data were collected at baseline (T0), after treatment (T1), and at the 12-month mark (T2) in terms of the following outcome measures: muscle strength, pain, fatigue, cramps, balance, walking speed, and ability. We included 37 CMT patients with a median age of 50.72 ± 13.31 years, with different forms: demyelinating (n = 28), axonal (n = 8), and mixed (n = 1). After intensive rehabilitation treatment, all outcomes significantly improved. This improvement was lost at the 1-year mark. Taken together, these findings suggest that an intensive rehabilitation program improves short-term symptoms and functional outcomes in a cohort of inpatients affected by mild to moderate CMT.

Acroparesthesias: An Overview

Acroparesthesia is a symptom characterized by a subjective sensation, such as numbness, tingling, prickling, and reduced sensation, affecting the extremities (fingers and toes). Despite its frequency, data regarding its diagnostic approach and management are scarce. The etiological diagnosis of acroparesthesia is sometimes challenging since it can be due to abnormality anywhere along the sensory pathway from the peripheral nervous system to the cerebral cortex. Acroparesthesia can reveal several diseases. It can be associated with rheumatic complaints such as arthritis or myalgia. Further cautions are required when paresthesia is acute (within days) in onset, rapidly progressive, severe, asymmetric, proximal, multifocal, or associated with predominant motor signs (limb weakness) or severe dysautonomia. Acroparesthesia may reveal Guillain-Barré syndrome or vasculitis, requiring rapid management. Acroparesthesia is a predominant symptom of polyneuropathy, typically distal and symmetric, often due to diabetes. However, it can occur in other diseases such as vitamin B12 deficiency, monoclonal gammopathy of undetermined significance, or Fabry's disease. Mononeuropathy, mainly carpal tunnel syndrome, remains the most common cause of acroparesthesia. Ultrasonography contributes to the diagnosis of nerve entrapment neuropathy by showing nerve enlargement, hypoechogenic nerve, and intraneural vascularity. Besides, it can reveal its cause, such as space-occupying lesions, anatomical nerve variations, or anomalous muscle. Ultrasonography is also helpful for entrapment neuropathy treatment, such as ultrasound-guided steroid injection or carpal tunnel release. The management of acroparesthesia depends on its causes. This article aimed to review and summarize current knowledge on acroparesthesia and its causes. We also propose an algorithm for the management of acroparesthesia.

The Regentime stem cell procedure, successful treatment for a Charcot-Marie-Tooth disease case

This report highlights the successful treatment of a Charcot-Marie-Tooth disease case using the Regentime stem cell procedure, suggesting its potential as a promising therapeutic approach for patients suffering from this challenging condition.

Vibration perception among children and adolescents with Charcot-Marie-tooth disease and implications for foot posture

BACKGROUND

Alterations in vibration perception among children and adolescents with Charcot-Marie-Tooth disease might explain observed changes in foot posture. Therefore, this cross-sectional study compared the vibration perception of the lower limbs in youths with and without Charcot-Marie-Tooth disease and verified the cut-off value of the distal vibration perception for the Charcot-Marie-Tooth group. In addition, associations between dynamic plantar pressure, vibration perception and isometric muscle strength were investigated.

METHODS

Participants aged 9-18 (Charcot-Marie-Tooth group n = 32; Typical group n = 32) had vibration perception measured by a 128-Hz graduated tuning fork. The static and dynamic foot posture were evaluated by the Foot Posture Index and pressure distribution measuring system, respectively. For the Charcot-Marie-Tooth group, a hand-held dynamometer evaluated the isometric muscle strength of the lower limbs.

FINDINGS

Children with Charcot-Marie-Tooth disease presented impaired vibration perception at the distal phalanx of the hallux and head of the first metatarsal compared to their typically developing peers, while adolescents with Charcot-Marie-Tooth disease showed impairment in all the tested regions compared to their typically developing peers. The cut-off value for vibration perception for participants with Charcot-Marie-Tooth disease was 5.7, considering the original grade of the tuning-fork 128 Hz. Among the associations established for the Charcot-Marie-Tooth group, a greater vibration perception at the distal phalanx of the hallux was associated with a longer rearfoot contact time (β = 31.02, p = 0.04).

INTERPRETATION

These new findings may guide the clinical evaluation and rehabilitation treatment for children and adolescents with Charcot-Marie-Tooth disease.

Clinical and Genetic Aspects of Childhood-Onset Demyelinating Charcot-Marie-Tooth's Disease in Brazil

Charcot-Marie-Tooth's disease (CMT) represents the most common inherited neuropathy. Most patients are diagnosed during late stages of disease course during adulthood. We performed a review of clinical, neurophysiological, and genetic diagnoses of 32 patients with genetically defined childhood-onset demyelinating CMT under clinical follow-up in a Brazilian Center for Neuromuscular Diseases from January 2015 to December 2019. The current mean age was 33.1 ± 18.3 years (ranging from 7 to 71 years) and mean age at defined genetic diagnosis was 36.1 ± 18.3 years. The mean age at onset was 6.1 ± 4.4 years. The most common initial complaint was bilateral pes cavus. The genetic basis included PMP22 duplication (CMT1A) ( n  = 18), GJB1 (CMTX1) ( n  = 5), MPZ (CMT1B) ( n  = 3), FIG4 (CMT4J) ( n  = 3), SH3TC2 (CMT4C) ( n  = 1), PLEKHG5 (CMTRIC) ( n  = 1), and PRX (CMT4F) ( n  = 1). Almost all patients ( n  = 31) presented with moderate or severe compromise in the CMT neuropathy score 2 with the highest values observed in CMT1B. Medical history disclosed obstructive sleep apnea ( n  = 5), aseptic meningitis ( n  = 1/ MPZ ), akinetic-rigid parkinsonism ( n  = 1/ FIG4 ), and overlapping chronic inflammatory demyelinating polyneuropathy ( n  = 1/ MPZ ). Motor conduction block was detected in three individuals ( PMP22 , FIG4 , MPZ ). Acute denervation occurred in seven patients. Nonuniform demyelinating patterns were seen in four individuals (two CMT1A, one CMT1B, and one CMTX1). Abnormal cerebral white matter findings were detected in CMT1A and CMTX1, while hypertrophic roots were seen in CMT1A, CMT1B, and CMTX1. Our study emphasizes a relative oligogenic basis in childhood-onset demyelinating CMT and atypical findings may be observed especially in MPZ , PMP22 , and GJB1 gene variants.

Approach to diagnosis, evaluation, and treatment of generalized and nonlocal dysesthesia: A review

Dysesthesia is an abnormal sensation in the skin that occurs in the absence of any extraordinary stimulus or other primary cutaneous disorders, excluding any delusions or tactile hallucinations. Clinicians have characterized dysesthesias to include sensations such as burning, tingling, pruritus, allodynia, hyperesthesia, or anesthesia. The etiology and pathogenesis of various generalized dysesthesias is largely unknown, though many dysesthesias have been associated with systemic pathologies including malignancy, infection, autoimmune disorders, and neuropathies. Dermatologists are often the first-line clinicians for patients presenting with such cutaneous findings, thus it is crucial for these physicians to be able to methodically work-up generalized dysesthesias to build a working differential diagnosis, follow up with key labs and/or imaging, and offer patients evidence-based treatment to relieve their symptoms. This broad literature review is an attempt to centralize key studies, cases, and series to help guide dermatologists in their assessment and evaluation of complaints of abnormal cutaneous sensations.

Combined RNA interference and gene replacement therapy targeting MFN2 as proof of principle for the treatment of Charcot-Marie-Tooth type 2A

Mitofusin-2 (MFN2) is an outer mitochondrial membrane protein essential for mitochondrial networking in most cells. Autosomal dominant mutations in the MFN2 gene cause Charcot-Marie-Tooth type 2A disease (CMT2A), a severe and disabling sensory-motor neuropathy that impacts the entire nervous system. Here, we propose a novel therapeutic strategy tailored to correcting the root genetic defect of CMT2A. Though mutant and wild-type MFN2 mRNA are inhibited by RNA interference (RNAi), the wild-type protein is restored by overexpressing cDNA encoding functional MFN2 modified to be resistant to RNAi. We tested this strategy in CMT2A patient-specific human induced pluripotent stem cell (iPSC)-differentiated motor neurons (MNs), demonstrating the correct silencing of endogenous MFN2 and replacement with an exogenous copy of the functional wild-type gene. This approach significantly rescues the CMT2A MN phenotype in vitro, stabilizing the altered axonal mitochondrial distribution and correcting abnormal mitophagic processes. The MFN2 molecular correction was also properly confirmed in vivo in the MitoCharc1 CMT2A transgenic mouse model after cerebrospinal fluid (CSF) delivery of the constructs into newborn mice using adeno-associated virus 9 (AAV9). Altogether, our data support the feasibility of a combined RNAi and gene therapy strategy for treating the broad spectrum of human diseases associated with MFN2 mutations.

[A case of Charcot-Marie-Tooth disease type 2 caused by homozygous MME gene mutation]

The patient is a 44-year-old man. His parents are consanguineous. He experienced muscle weakness in his toe and distal tingling sensation in his feet at 42 years of age, which gradually progressed. Additionally, a marked cyanotic discoloration of the feet appeared and worsened progressively. Neurological examination revealed loss of tendon reflexes and distal muscle weakness in the lower extremities. Findings from nerve conduction studies indicated axonal polyneuropathy. Upon detection of the MME gene mutation, the patient was diagnosed with autosomal-recessive Charcot-Marie-Tooth disease 2T (ARCMT2T). In this case, cyanosis of the lower extremities possibly was associated with ARCMT2T, and it was suggested to be due to neprilysin deletion linked with the MME mutation. This represents the first documented occurrence of cyanosis as a distinctive feature of CMT with MME mutation.

PINK1 and Parkin rescue motor defects and mitochondria dysfunction induced by a patient-derived HSPB3 mutant in Drosophila models

Small heat shock proteins (sHSPs) are ATP-independent molecular chaperones with the α-crystalline domain that is critical to their chaperone activity. Within the sHSP family, three (HSPB1, HSPB3, and HSPB8) proteins are linked with inherited peripheral neuropathies, including distal hereditary motor neuropathy (dHMN) and Charco-Marie-Tooth disease (CMT). In this study, we introduced the HSPB3 Y118H (HSPB3Y118H) mutant gene identified from the CMT2 family in Drosophila. With a missense mutation on its α-crystalline domain, this human HSPB3 mutant gene induced a loss of motor activity accompanied by reduced mitochondrial membrane potential in fly neuronal tissues. Moreover, mitophagy, a critical mechanism of mitochondrial quality control, is downregulated in fly motor neurons expressing HSPB3Y118H. Surprisingly, PINK1 and Parkin, the core regulators of mitophagy, successfully rescued these motor and mitochondrial abnormalities in HSPB3 mutant flies. Results from the first animal model of HSPB3 mutations suggest that mitochondrial dysfunction plays a critical role in HSPB3-associated human pathology.

Magnetic resonance neurography techniques in the pediatric population

The use of magnetic resonance imaging (MRI) in the evaluation of the central extracranial nervous system, namely the brachial and lumbosacral plexuses, is well established and has been performed for many years. Only recently after numerous advances in MRI, has image quality been sufficient to properly visualize small structures, such as nerves in the extremities. Despite the advances, peripheral MR Neurography remains a complex and difficult examination to perform, especially in the pediatric patient population, in which the risk for motion artifact and compliance is always of concern. Thus, technical aspects of the MR imaging protocol must be flexible but robust, to balance image quality with scan time, in a patient population of varying sizes. An additional important step for reliably performing a successful MR Neurography examination is the non-technical pre-imaging preparation, which includes patient/family education and open communication with referring teams. This paper will discuss in detail the individual technical and non-technical/operational aspects of peripheral MR Neurography, to help guide in building a successful program in the pediatric population.

Gastrointestinal and nutritional care in pediatric neuromuscular disorders

Neuromuscular diseases (NMDs) affect the development and growth of the neuromuscular system in children. The pathology can occur anywhere along the neuromuscular pathway, from the brain to the nerves to the muscle fibers. These diseases have a profound impact on the quality of life not only of children but also of their families. The predominant manifestation in NMDs is hypotonia, which leads to muscle weakness and fatigue, reduced mobility, and decreased physical performance. However, multiple organ systems can be affected, with resulting orthopedic, cardiac, infectious, respiratory, and nutritional problems. Children with NMD present an increased risk for several dietary and feeding difficulties because of their neuromuscular diagnosis, presentation, and severity. These problems include chronic gastrointestinal issues (constipation, dysphagia, gastroesophageal reflux, and diarrhea), dysphagia, malnutrition, and body composition alterations. As a result, compared to the overall pediatric population, infants and children with NMD are more likely to be malnourished, ranging from failure to thrive to overweight or obesity. Disease-specific guidelines vary in level of detail and recommendations for dietary management. Overall, nutritional data available are sparse, with the exception of Duchenne muscular dystrophy, spinal muscular atrophy, and congenital muscular dystrophy. The purpose of this review is to describe the spectrum of nutritional challenges in children with NMD and to summarize the main dietary and gastrointestinal recommendations for each neuromuscular disorder to provide guidance for daily clinical practice.

Effect of Ankle-Foot Orthoses in Pediatric Patients with Hereditary Motor-Sensory Neuropathy: A Case Series Study

(1) Aims: to evaluate the effect on gait performance and standing stability of ankle-foot orthoses (AFO) in pediatric patients with hereditary motor-sensory neuropathy (HMSN). (2) Methods: a retrospective case-series study including three adolescents (S1, S2, S3, mean age 14 years) with HMSN. The subjects were evaluated barefoot, with carbon AFO (Botter) and with solid AFO (SAFO) by means of: gait analysis, stabilometry and gait functional tests (10 Meter Walk Test, 2 Minute Walk Test). Finally, the CSD-OPUS questionnaire was administered to the assess satisfaction and impact of the orthoses on life quality. (3) Results: orthoses improved gait and stability performance. Botter allowed greater ankle movement than SAFO and provided greater push-off power. This, combined with the carbon elastic energy return, might explain better performances in the 2MWT, with a larger distance traveled compared to SAFO for both S1 (110 m vs. 72 m) and S2 (170 m vs. 155 m) and, compared to barefoot walking, also for S3 (211 m vs. 160 m), for which SAFO analysis was not available. Both orthoses improved performance at the stabilometric analysis. The CSD-OPUS questionnaire showed a significantly higher level of satisfaction with Botter for the subjects (S1, S2) who completed the comparison. (4) Conclusions: Both orthoses improved gait and standing, though Botter proved to be better tolerated and more effective in improving gait endurance.

Physiological and engineered tRNA aminoacylation

Aminoacyl-tRNA synthetases form the protein family that controls the interpretation of the genetic code, with tRNA aminoacylation being the key chemical step during which an amino acid is assigned to a corresponding sequence of nucleic acids. In consequence, aminoacyl-tRNA synthetases have been studied in their physiological context, in disease states, and as tools for synthetic biology to enable the expansion of the genetic code. Here, we review the fundamentals of aminoacyl-tRNA synthetase biology and classification, with a focus on mammalian cytoplasmic enzymes. We compile evidence that the localization of aminoacyl-tRNA synthetases can be critical in health and disease. In addition, we discuss evidence from synthetic biology which made use of the importance of subcellular localization for efficient manipulation of the protein synthesis machinery. This article is categorized under: RNA Processing Translation > Translation Regulation RNA Processing > tRNA Processing RNA Export and Localization > RNA Localization.

Homozygous COQ7 mutation: a new cause of potentially treatable distal hereditary motor neuropathy

Distal hereditary motor neuropathy represents a group of motor inherited neuropathies leading to distal weakness. We report a family of two brothers and a sister affected by distal hereditary motor neuropathy in whom a homozygous variant c.3G>T (p.1Met?) was identified in the COQ7 gene. This gene encodes a protein required for coenzyme Q10 biosynthesis, a component of the respiratory chain in mitochondria. Mutations of COQ7 were previously associated with severe multi-organ disorders characterized by early childhood onset and developmental delay. Using patient blood samples and fibroblasts derived from a skin biopsy, we investigated the pathogenicity of the variant of unknown significance c.3G>T (p.1Met?) in the COQ7 gene and the effect of coenzyme Q10 supplementation in vitro. We showed that this variation leads to a severe decrease in COQ7 protein levels in the patient's fibroblasts, resulting in a decrease in coenzyme Q10 production and in the accumulation of 6-demethoxycoenzyme Q10, the COQ7 substrate. Interestingly, such accumulation was also found in the patient's plasma. Normal coenzyme Q10 and 6-demethoxycoenzyme Q10 levels were restored in vitro by using the coenzyme Q10 precursor 2,4-dihydroxybenzoic acid, thus bypassing the COQ7 requirement. Coenzyme Q10 biosynthesis deficiency is known to impair the mitochondrial respiratory chain. Seahorse experiments showed that the patient's cells mainly rely on glycolysis to maintain sufficient ATP production. Consistently, the replacement of glucose by galactose in the culture medium of these cells reduced their proliferation rate. Interestingly, normal proliferation was restored by coenzyme Q10 supplementation of the culture medium, suggesting a therapeutic avenue for these patients. Altogether, we have identified the first example of recessive distal hereditary motor neuropathy caused by a homozygous variation in the COQ7 gene, which should thus be included in the gene panels used to diagnose peripheral inherited neuropathies. Furthermore, 6-demethoxycoenzyme Q10 accumulation in the blood can be used to confirm the pathogenic nature of the mutation. Finally, supplementation with coenzyme Q10 or derivatives should be considered to prevent the progression of COQ7-related peripheral inherited neuropathy in diagnosed patients.

Clinical and mutational spectrum of paediatric Charcot-Marie-Tooth disease in a large cohort of Chinese patients

Background: Charcot-Marie-Tooth disease (CMT) is the most common inherited neurological disorder suffered in childhood. To date, the disease features have not been extensively characterized in the Chinese paediatric population. In this study, we aimed to analyse the clinical profiles and genetic distributions of a paediatric CMT cohort in China. Methods: A total of 181 paediatric CMT patients were enrolled. After preexcluding PMP22 duplication/deletion by multiplex ligation-dependent probe amplification (MLPA), Sanger sequencing, targeted next-generation sequencing (NGS) or whole-exome sequencing (WES) was performed to obtain a genetic diagnosis. Detailed information was collected to explore the spectrum of subtypes and genotype-phenotype correlations. Results: Pathogenic mutations were identified in 68% of patients in this study; with PMP22 duplication, MFN2 and GJB1 were the most frequent disease-causing genes. Of note, respect to the higher prevalence worldwide, CMT1A (18.2%) was relatively lower in our cohort. Besides, the mean age at onset (8.3 ± 5.7 years) was significantly older in our series. In genotype-phenotype analyse, PMP22 point mutations were considered the most severe genotypes and were mostly de novo. In addition, the de novo mutations were identified in up to 12.7% of all patients, which was higher than that in other studies. Conclusion: We identified a relatively lower detection rate of PMP22 duplication and a higher frequency of de novo variants among paediatric patients in China. We also identified the genetic and phenotypic heterogeneity of this cohort, which may provide clues for clinicians in directing genetic testing strategies for Chinese patients with early-onset CMT.

Screening for PRX mutations in a large Chinese Charcot-Marie-Tooth disease cohort and literature review

Background

Periaxins (encoded by PRX) play an important role in the stabilization of peripheral nerve myelin. Mutations in PRX can lead to Charcot-Marie-Tooth disease type 4F (CMT4F).

Methods

In this study, we screened for PRX mutations using next-generation sequencing and whole-exome sequencing in a large Chinese CMT cohort consisting of 465 unrelated index patients and 650 healthy controls. Sanger sequencing was used for the validation of all identified variants. We also reviewed all previously reported PRX-related CMT cases and summarized the clinical manifestations and genetic features of PRX-related CMTs.

Results

The hit rate for biallelic PRX variants in our cohort of Chinese CMT patients was 0.43% (2/465). One patient carried a previously unreported splice-site mutation (c.25_27 + 9del) compound heterozygous with a known nonsense variant. Compiling data on CMT4F cases and PRX variants from the medical literature confirmed that early-onset (95.2%), distal amyotrophy or weakness (94.0%), feet deformity (75.0%), sensory impairment or sensory ataxia (65.5%), delayed motor milestones (60.7%), and spinal deformity (59.5%) are typical features for CMT4F. Less frequent features were auditory impairments, respiratory symptoms, late onset, dysarthria or hoarseness, ophthalmic problems, and central nervous system involvement. The two cases with biallelic missense mutations have later onset age than those with nonsense or frameshift mutations. We did not note clear correlations between the type and site of mutations and clinical severity or distinct constellations of symptoms.

Conclusion

Consistent with observations in other countries and ethnic groups, PRX-related CMT is rare in China. The clinical spectrum is wider than previously anticipated.

A Retrospective Bayesian Design of Experiment (B-DOE) on Drug Reposition Candidates for Treatment of Charcot-Marie-Tooth Neuropathy

Bayesian design of experiment (B-DOE) uses the principle of Bayesian Epistemology that explain the evidence as a logical-probalistic coherence on the basis of rational degrees of belief (or degrees of confidence). The researcher has design the (B-DOE) using Multilevel Hierarchy (MH), and data that may be obtained at the weak to moderate evidence level (literature, biological. Mechanism, computational and retrospective) may be helpful to identify bioactive compounds for treating (CMT) and provide the knowledge on pathogenesis, prognostic of the disease and collective mechanism of drug of action. The investigators will classify the evidence on the basis of hierarchy as moderate and weak, which will ultimately help to study new promising bioactive compounds potentially able to solve some of the issues related to CMT.

An Integrated Review of Carpal Tunnel Syndrome: New Insights to an Old Problem

Carpal tunnel syndrome (CTS) is a common entrapment neuropathy characterized by pain, numbness, and impaired function of the hand due to compression of the median nerve at the level of the wrist. Although CTS can develop from repetitive strain, injury, or medical conditions, there are also congenital and genetic risk factors that can predispose individuals to the condition. With respect to anatomical factors, some individuals are born with a smaller carpal tunnel, which increases their susceptibility to median nerve compression. Variations in specific genes, such as those encoding proteins involved in extracellular matrix remodeling, inflammation, and nerve function, have also been linked to an increased risk for CTS. CTS is associated with a high cost of health care maintenance and loss of work productivity. Therefore, it is vital that primary care physicians fully understand the anatomy, epidemiology, pathophysiology, etiology, and risk factors of CTS, so they can be proactive in prevention, diagnosing, and guiding proper treatment. This integrated review also provides insights into how biological, genetic, environmental, and occupational factors interact with structural elements to determine who is most likely to acquire and suffer from CTS. Keeping health practitioners abreast of all the factors that could impact CTS should go a long way in decreasing the health care and socioeconomic burden of CTS.

Quantitative assessment of plantar pressure patterns in relation to foot deformities in people with hereditary motor and sensory neuropathies

BACKGROUND

Hereditary motor and sensory neuropathies (HMSN), also known as Charcot-Marie-Tooth disease, are characterized by affected peripheral nerves. This often results in foot deformities that can be classified into four categories: (1) plantar flexed first metatarsal, neutral hindfoot, (2) plantar flexed first metatarsal, correctable hindfoot varus, (3) plantar flexed first metatarsal, uncorrectable hindfoot varus, and (4) hindfoot valgus. To improve management and for the evaluation of surgical interventions, a quantitative evaluation of foot function is required. The first aim of this study was to provide insight into plantar pressure of people with HMSN in relation to foot deformities. The second aim was to propose a quantitative outcome measure for the evaluation of surgical interventions based on plantar pressure.

METHODS

In this historic cohort study, plantar pressure measurements of 52 people with HMSN and 586 healthy controls were evaluated. In addition to the evaluation of complete plantar pressure patterns, root mean square deviations (RMSD) of plantar pressure patterns from the mean plantar pressure pattern of healthy controls were calculated as a measure of abnormality. Furthermore, center of pressure trajectories were calculated to investigate temporal characteristics. Additionally, plantar pressure ratios of the lateral foot, toes, first metatarsal head, second/third metatarsal heads, fifth metatarsal head, and midfoot were calculated to measure overloading of foot areas.

RESULTS

Larger RMSD values were found for all foot deformity categories compared to healthy controls (p < 0.001). Evaluation of the complete plantar pressure patterns revealed differences in plantar pressure between people with HMSN and healthy controls underneath the rearfoot, lateral foot, and second/third metatarsal heads. Center of pressure trajectories differed between people with HMSN and healthy controls in the medio-lateral and anterior-posterior direction. The plantar pressure ratios, and especially the fifth metatarsal head pressure ratio, differed between healthy controls and people with HMSN (p < 0.05) and between the four foot deformity categories (p < 0.05).

CONCLUSIONS

Spatially and temporally distinct plantar pressure patterns were found for the four foot deformity categories in people with HMSN. We suggest to consider the RMSD in combination with the fifth metatarsal head pressure ratio as outcome measures for the evaluation of surgical interventions in people with HMSN.

Natural history of ankle function during gait in youth with Charcot-Marie-Tooth disease types 1 and 2

BACKGROUND

Charcot-Marie-Tooth disease (CMT) can cause progressive muscle weakness and contracture, leading to gait abnormalities such as increased and delayed peak ankle dorsiflexion and reduced ankle power generation in terminal stance. Understanding strength loss on ankle function during gait is important for interpreting treatment outcomes and evaluating new therapies designed to improve gait.

RESEARCH QUESTION

Do ankle kinematics and kinetics vary as a function of age, disease progression with associated loss of muscle strength and CMT type in youth with CMT types 1 and 2?

METHODS

A prospective convenience sample of 45 participants with CMT1 and 2, ages 7-22 years, underwent comprehensive gait analysis. Seventeen patients underwent repeat analyses totaling 67 tests. Generalized mixed effects linear modeling was used to compare CMT1 versus CMT2 and to examine the effects of age on ankle strength, range of motion, kinematics, and kinetics within each CMT type.

RESULTS

Plantarflexor and dorsiflexor strength were less in CMT2 compared with CMT1 (p ≤ 0.05), while peak dorsiflexion in terminal stance (TST) was greater (p = 0.02). Peak plantarflexion moment and power generation were also less in CMT2 (p ≤ 0.02). In CMT1, peak dorsiflexion in TST increased with age through 13 years (p = 0.004); then plateaued in the normal range (p = 0.73). Peak ankle angle in mid-swing was closely related to the angle in TST (p < 0.001) following a similar pattern with age. In CMT2, no significant associations were observed between age, peak dorsiflexion in TST, and peak ankle angle in mid-swing (p ≥ 0.19). There were no consistent trends with age for individual patients with repeat tests.

SIGNIFICANCE

The heterogeneity of joint level impairments and gait kinematics and kinetics point to the importance of having an in-depth understanding of gait at the individual patient level using comprehensive gait analysis including valid and reliable strength measures.

PINK1 and Parkin Ameliorate the Loss of Motor Activity and Mitochondrial Dysfunction Induced by Peripheral Neuropathy-Associated HSPB8 Mutants in Drosophila Models

Charcot–Marie–Tooth disease (CMT) is a group of inherited peripheral nerve disorders characterized by progressive muscle weakness and atrophy, sensory loss, foot deformities and steppage gait. Missense mutations in the gene encoding the small heat shock protein HSPB8 (HSP22) have been associated with hereditary neuropathies, including CMT. HSPB8 is a member of the small heat shock protein family sharing a highly conserved α-crystallin domain that is critical to its chaperone activity. In this study, we modeled HSPB8 mutant-induced neuropathies in Drosophila. The overexpression of human HSPB8 mutants in Drosophila neurons produced no significant defect in fly development but led to a partial reduction in fly lifespan. Although these HSPB8 mutant genes failed to induce sensory abnormalities, they reduced the motor activity of flies and the mitochondrial functions in fly neuronal tissue. The motor defects and mitochondrial dysfunction were successfully restored by PINK1 and parkin, which are Parkinson’s disease-associated genes that have critical roles in maintaining mitochondrial function and integrity. Consistently, kinetin riboside, a small molecule amplifying PINK1 activity, also rescued the loss of motor activity in our HSPB8 mutant model.

The evolution of comprehensive genetic analysis in neurology: Implications for precision medicine

Technological advancements have facilitated the availability of reliable and thorough genetic analysis in many medical fields, including neurology. In this review, we focus on the importance of selecting the appropriate genetic test to aid in the accurate identification of disease utilizing currently employed technologies for analyzing monogenic neurological disorders. Moreover, the applicability of comprehensive analysis via NGS for various genetically heterogeneous neurological disorders is reviewed, revealing its efficiency in clarifying a frequently cloudy diagnostic picture and delivering a conclusive and solid diagnosis that is essential for the proper management of the patient. The feasibility and effectiveness of medical genetics in neurology require interdisciplinary cooperation among several medical specialties and geneticists, to select and perform the most relevant test according to each patient's medical history, using the most appropriate technological tools. The prerequisites for a comprehensive genetic analysis are discussed, highlighting the utility of appropriate gene selection, variant annotation, and classification. Moreover, genetic counseling and interdisciplinary collaboration could improve diagnostic yield further. Additionally, a sub-analysis is conducted on the 1,502,769 variation records with submitted interpretations in the Clinical Variation (ClinVar) database, with a focus on neurology-related genes, to clarify the value of suitable variant categorization. Finally, we review the current applications of genetic analysis in the diagnosis and personalized management of neurological patients and the advances in the research and scientific knowledge of hereditary neurological disorders that are evolving the utility of genetic analysis towards the individualization of the treatment strategy.

[Neurological disorders and hereditary podocytopathies: Some fascinating pathophysiological overlaps]

Genetic studies of hereditary steroid resistant nephrotic syndrome (SRNS) have identified more than 60 genes involved in the development of single-gene, isolated or syndromic forms of hereditary podocytoapthies. Sometimes, syndromic SRNS is associated with neurological disorders. Over the past decades, various studies have established links between the podocyte, an epithelial glomerular cell involved in the renal filtration barrier, and neuronal cells, both morphologically (slit diaphragm and synapse) and functionally (signaling platforms). Variants of genes encoding proteins expressed in different compartments of the podocyte and neurons are responsible for phenotypes associating renal lesions with proteinuria to central and/or peripheral neurological disorders. In this review, we aim to focus on genetic syndromes associating proteinuria and neurological disease and to present the latest advances in the description of these neuro-renal disorders.

Pathogenic PSAT1 Variants and Autosomal Recessive Axonal Charcot-Marie-Tooth Disease With Ichthyosis

BACKGROUND

Biallelic pathogenic phosphoserine aminotransferase 1 (PSAT1) variants generally cause a severe phenotype predominantly involving the central nervous system. Here, for the first time, we report two patients harboring pathogenic PSAT1 variants only manifested as polyneuropathy and ichthyosis.

METHODS

Two patients from unrelated families presenting with polyneuropathy and ichthyosis were enrolled. Whole exome sequencing was performed to identify possible disease-causing variants. Their clinical, electrophysiological, imaging, biochemical, and pathologic changes were in detail assessed and investigated.

RESULTS

Homozygous variant c.43G>C and compound heterozygous variants c.112A>C and c.43G>C in PSAT1 were identified in patients 1 and 2, respectively. Nerve conduction studies revealed preserved or mild slowing motor nerve conduction velocities of the median nerves in the two patients, whereas the compound motor action potential in patient 1 was severely decreased. Brain magnetic resonance imaging of the two patients found no abnormalities. Median nerve enlargement was observed on ultrasound in patient 1. Both patients had normal level of serine and glycine in plasma and cerebrospinal fluid. Sural nerve biopsy found severe loss of myelinated fibers. Electron microscopy revealed neurofilament accumulation and mitochondrial aggregation in axons. Both variants in PSAT1 were classified as likely pathogenic or pathogenic variants according to the standard guidelines.

CONCLUSIONS

Our study confirms that pathogenic PSAT1 variants can cause a mild phenotype, predominantly as autosomal recessive axonal Charcot-Marie-Tooth disease.

A mysterious triangle of blood, bones, and nerves

The relationship between bone tissue and bone marrow, which is responsible for hematopoiesis, is inseparable. Osteoblasts and osteocytes, which produce and consist of bone tissue, regulate the function of hematopoietic stem cells (HSC), the ancestors of all hematopoietic cells in the bone marrow. The peripheral nervous system finely regulates bone remodeling in bone tissue and modulates HSC function within the bone marrow, either directly or indirectly via modification of the HSC niche function. Peripheral nerve signals also play an important role in the development and progression of malignant tumors (including hematopoietic tumors) and normal tissues, and peripheral nerve control is emerging as a potential new therapeutic target. In this review, we summarize recent findings on the linkage among blood system, bone tissue, and peripheral nerves.

Novel Variants in MPV17, PRX, GJB1, and SACS Cause Charcot-Marie-Tooth and Spastic Ataxia of Charlevoix-Saguenay Type Diseases

Charcot-Marie-Tooth disease (CMT) and autosomal recessive spastic ataxia of Charlevoix-Saguenay type (ARSACS) are large heterogeneous groups of sensory, neurological genetic disorders characterized by sensory neuropathies, muscular atrophies, abnormal sensory conduction velocities, and ataxia. CMT2EE (OMIM: 618400) is caused by mutations in MPV17 (OMIM: 137960), CMT4F (OMIM: 614895) is caused by PRX (OMIM: 605725), CMTX1 (OMIM: 302800) is caused by mutations in GJB1 (OMIM: 304040), and ARSACS (OMIM: 270550) is caused by mutations in SACS (OMIM: 604490). In this study, we enrolled four families: DG-01, BD-06, MR-01, and ICP-RD11, with 16 affected individuals, for clinical and molecular diagnoses. One patient from each family was analyzed for whole exome sequencing and Sanger sequencing was done for the rest of the family members. Affected individuals of families BD-06 and MR-01 show complete CMT phenotypes and family ICP-RD11 shows ARSACS type. Family DG-01 shows complete phenotypes for both CMT and ARSACS types. The affected individuals have walking difficulties, ataxia, distal limb weakness, axonal sensorimotor neuropathies, delayed motor development, pes cavus, and speech articulations with minor variations. The WES analysis in an indexed patient of family DG-01 identified two novel variants: c.83G>T (p.Gly28Val) in MPV17 and c.4934G>C (p.Arg1645Pro) in SACS. In family ICP-RD11, a recurrent mutation that causes ARSACS, c.262C>T (p.Arg88Ter) in SACS, was identified. Another novel variant, c.231C>A (p.Arg77Ter) in PRX, which causes CMT4F, was identified in family BD-06. In family MR-01, a hemizygous missense variant c.61G>C (p.Gly21Arg) in GJB1 was identified in the indexed patient. To the best of our knowledge, there are very few reports on MPV17, SACS, PRX, and GJB1 causing CMT and ARSACS phenotypes in the Pakistani population. Our study cohort suggests that whole exome sequencing can be a useful tool in diagnosing complex multigenic and phenotypically overlapping genetic disorders such as Charcot-Marie-Tooth disease (CMT) and spastic ataxia of Charlevoix-Saguenay type.

Playing Disability Rugby League with Charcot-Marie-Tooth Disease: A Case Study

Charcot-Marie-Tooth (CMT) disease is a common inherited neurological disorder that causes damage to peripheral nerves. Reports of CMT patients participating in team-based sports such as disability rugby league are scarce. The objective of this case report was to evaluate the benefits of participation in disability rugby league in a 50-year-old male with CMT. Leg muscle mass and strength was worse for the case subject compared to two age-matched CMT participants with an exercise history; however, evidence of greater function in the case subject was observed through better 6-min walk test performance. Performance in a series of sport specific tests was noticeably worse for the case subject compared to a fellow rugby league player (age matched) with cerebral palsy. Inferior in-game performance was observed for the case subject compared to his fellow rugby league player in terms of distance covered, top running speed, and intensity. However, the case subject may have assumed a different role when playing as evident by the different behaviours he displayed during the games (i.e., less player contacts, tackles, or touches, but more passes of the ball). This case study provides information concerning disability rugby league as an adjunctive mode of treatment for CMT populations.