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Objective: The paucity of longitudinal natural history studies in MPZ neuropathy remains a barrier to clinical trials. We have completed a longitudinal natural history study in patients with MPZ neuropathies across 13 sites of the Inherited Neuropathies Consortium. Methods: Change in Charcot–Marie–Tooth Examination Score (CMTES) and Rasch modified CMTES (CMTES‐R) were evaluated using longitudinal regression over a 5‐year period in subjects with MPZ neuropathy. Data from 139 patients with MPZ neuropathy were examined. Results: The average baseline CMTES and CMTES‐R were 10.84 (standard deviation [SD] = 6.0, range = 0–28) and 14.60 (SD = 7.56, range = 0–32), respectively. A mixed regression model showed significant change in CMTES at years 2–5 (mean change from baseline of 0.87 points at 2 years, p = 0.008). Subgroup analysis revealed greater change in CMTES at 2 years in subjects with axonal as compared to demyelinating neuropathy (mean change of 1.30 points [p = 0.016] vs 0.06 points [p = 0.889]). Patients with a moderate baseline neuropathy severity also showed more notable change, by estimate, than those with mild or severe neuropathy (mean 2‐year change of 1.14 for baseline CMTES 8–14 [p = 0.025] vs −0.03 for baseline CMTES 0–7 [p = 0.958] and 0.25 for baseline CMTES ≥ 15 [p = 0.6897]). The progression in patients harboring specific MPZ mutations was highly variable. Interpretation: CMTES is sensitive to change over time in adult patients with axonal but not demyelinating forms of MPZ neuropathy. Change in CMTES was greatest in patients with moderate baseline disease severity. These findings will inform future clinical trials of MPZ neuropathies. ANN NEUROL 2023;93:563–576 [ABSTRACT FROM AUTHOR]

Introduction: Balance impairment contributes to gait dysfunction, falls, and reduced quality of life in adults with Charcot-Marie-Tooth disease (CMT) but has been minimally examined in pediatric CMT.Methods: The CMT Pediatric Scale (CMTPedS) was administered to 520 children with CMT. Associations between balance function (Bruininks-Oseretsky Test of Motor Proficiency [BOT-2]) and sensorimotor and gait impairments were investigated.Results: Daily trips/falls were reported by 42.3% of participants. Balance (BOT-2) varied by CMT subtype, was impaired in 42% of 4-year-olds, and declined with age (P < 0.001). Vibration (P < 0.001), pinprick (P < 0.004), ankle dorsiflexion strength (P < 0.001), and foot alignment (P < 0.004) were associated with BOT-2 balance (adjusted R2 = 0.28). The visual dependence of balance increased with age.Discussion: Balance impairment occurs from a young age in children with CMT. Balance intervention studies are required in pediatric CMT and should consider the degree of sensorimotor impairment, foot malalignment, and visual dependence. Muscle Nerve, 2019. [ABSTRACT FROM AUTHOR]

The CMT Pediatric Scale (CMTPedS) is a reliable, valid, and responsive clinical outcome measure of disability in children with CMT. The aim of this study was to identify the most responsive patient subset(s), based on the standardized response mean (SRM), to optimize the CMTPedS as a primary outcome measure for upcoming clinical trials. Analysis was based on a 2‐year natural history data from 187 children aged 3–20 years with a range of CMT genetic subtypes. Subsets based on age (3–8 years), disability level (CMTPedS score 0–14), and CMT type (CMT1A) increased the SRM of the CMTPedS considerably. Refining the inclusion criteria in clinical trials to younger, mildly affected cases of CMT1A optimizes the responsiveness of the CMTPedS. [ABSTRACT FROM AUTHOR]

Mitofusin-2 (MFN2) is one of two ubiquitously expressed homologous proteins in eukaryote cells, playing a critical role in mitochondrial fusion. Mutations in MFN2 (most commonly autosomal dominant) cause Charcot-Marie-Tooth disease type 2A (CMT2A), the commonest axonal form of CMT, with significant allelic heterogeneity. Previous, moderately-sized, cross sectional genotype-phenotype studies of CMT2A have described the phenotypic spectrum of the disease, but longitudinal natural history studies are lacking. In this large multicentre prospective cohort study of 196 patients with dominant and autosomal recessive CMT2A, we present an in-depth genotype-phenotype study of the baseline characteristics of patients with CMT2A and longitudinal data (1-2 years) to describe the natural history. A childhood onset of autosomal dominant CMT2A is the most predictive marker of significant disease severity and is independent of the disease duration. When compared to adult onset autosomal dominant CMT2A, it is associated with significantly higher rates of use of ankle-foot orthoses, full-time use of wheelchair, dexterity difficulties and also has significantly higher CMT Examination Score (CMTESv2) and CMT Neuropathy Score (CMTNSv2) at initial assessment. Analysis of longitudinal data using the CMTESv2 and its Rasch-weighted counterpart, CMTESv2-R, show that over 1 year, the CMTESv2 increases significantly in autosomal dominant CMT2A (mean change 0.84 ± 2.42; two-tailed paired t-test P = 0.039). Furthermore, over 2 years both the CMTESv2 (mean change 0.97 ± 1.77; two-tailed paired t-test P = 0.003) and the CMTESv2-R (mean change 1.21 ± 2.52; two-tailed paired t-test P = 0.009) increase significantly with respective standardized response means of 0.55 and 0.48. In the paediatric CMT2A population (autosomal dominant and autosomal recessive CMT2A grouped together), the CMT Pediatric Scale increases significantly both over 1 year (mean change 2.24 ± 3.09; two-tailed paired t-test P = 0.009) and over 2 years (mean change 4.00 ± 3.79; two-tailed paired t-test P = 0.031) with respective standardized response means of 0.72 and 1.06. This cross-sectional and longitudinal study of the largest CMT2A cohort reported to date provides guidance for variant interpretation, informs prognosis and also provides natural history data that will guide clinical trial design., (© The Author(s) (2021). Published by Oxford University Press on behalf of the Guarantors of Brain.)