Cross-sectional analysis of a large cohort with X-linked Charcot-Marie-Tooth disease (CMTX1)

OBJECTIVE: To extend the phenotypic description of Charcot-Marie-Tooth disease (CMTX1) and to draw new genotype-phenotype relationships. METHODS: Mutations in GJB1 cause the main X-linked form of CMTX (CMTX1). We report cross-sectional data from 160 patients (from 120 different families, with 89 different mutations) seen at the Inherited Neuropathies Consortium centers. RESULTS: We evaluated 87 males who had a mean age of 41 years (range 10-78 years) and 73 females who had a mean age of 46 years (range 15-84 years). Sensory-motor polyneuropathy affects both sexes, more severely in males than in females, and there was a strong correlation between age and disease burden in males but not in females. Compared with females, males had more severe reduction in motor and sensory neurophysiology parameters. In contrast to females, the radial nerve sensory response in older males tended to be more severely affected compared with younger males. Median and ulnar nerve motor amplitudes were also more severely affected in older males, whereas ulnar nerve motor potentials tended to be more affected in older females. Conversely, there were no statistical differences between the sexes in other features of the disease, such as problems with balance and hand dexterity. CONCLUSIONS: In the absence of a phenotypic correlation with specific GJB1 mutations, sex-specific distinctions and clinically relevant attributes need to be incorporated into the measurements for clinical trials in people with CMTX1. CLINICALTRIALSGOV IDENTIFIER: NCT01193075

Disease Progression in CMT related to MPZ Mutations: A Longitudinal Study

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 Neuropathy Consortium. METHODS: Change in Charcot Marie Tooth Examination scores (CMTES) and Rasch modified CMTES (CMTES-R) scores 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 scores were 10.84 (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) versus 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), versus -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 scores are 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. This article is protected by copyright. All rights reserved