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See Karakaya and Wirth (doi:10.1093/brain/awz273) for a scientific commentary on this article. Neurofascin (NFASC) isoforms are immunoglobulin cell adhesion molecules involved in node of Ranvier assembly. Efthymiou et al. identify biallelic NFASC variants in ten unrelated patients with a neurodevelopmental disorder characterized by variable degrees of central and peripheral involvement. Abnormal expression of Nfasc155 is accompanied by severe loss of myelinated fibres., Axon pathfinding and synapse formation are essential processes for nervous system development and function. The assembly of myelinated fibres and nodes of Ranvier is mediated by a number of cell adhesion molecules of the immunoglobulin superfamily including neurofascin, encoded by the NFASC gene, and its alternative isoforms Nfasc186 and Nfasc140 (located in the axonal membrane at the node of Ranvier) and Nfasc155 (a glial component of the paranodal axoglial junction). We identified 10 individuals from six unrelated families, exhibiting a neurodevelopmental disorder characterized with a spectrum of central (intellectual disability, developmental delay, motor impairment, speech difficulties) and peripheral (early onset demyelinating neuropathy) neurological involvement, who were found by exome or genome sequencing to carry one frameshift and four different homozygous non-synonymous variants in NFASC. Expression studies using immunostaining-based techniques identified absent expression of the Nfasc155 isoform as a consequence of the frameshift variant and a significant reduction of expression was also observed in association with two non-synonymous variants affecting the fibronectin type III domain. Cell aggregation studies revealed a severely impaired Nfasc155-CNTN1/CASPR1 complex interaction as a result of the identified variants. Immunofluorescence staining of myelinated fibres from two affected individuals showed a severe loss of myelinated fibres and abnormalities in the paranodal junction morphology. Our results establish that recessive variants affecting the Nfasc155 isoform can affect the formation of paranodal axoglial junctions at the nodes of Ranvier. The genetic disease caused by biallelic NFASC variants includes neurodevelopmental impairment and a spectrum of central and peripheral demyelination as part of its core clinical phenotype. Our findings support possible overlapping molecular mechanisms of paranodal damage at peripheral nerves in both the immune-mediated and the genetic disease, but the observation of prominent central neurological involvement in NFASC biallelic variant carriers highlights the importance of this gene in human brain development and function.

Processing of time in the millisecond range seems to depend on cerebellar function and it can be assessed by using the somatosensory temporal discrimination threshold testing. No studies have yet investigated this temporal discrimination task in patients with cerebellar atrophy. Eleven patients with degenerative cerebellar ataxia and 11 controls underwent somatosensory temporal discrimination threshold evaluation. The degree of cerebellar dysfunction was measured by the International Cooperative Ataxia Rating Scale. Somatosensory temporal discrimination threshold was higher in patients compared to controls for each stimulated site (hand, neck, and eye). Age, disease duration, and International Cooperative Ataxia Rating Scale scores were not correlated to somatosensory temporal discrimination threshold. Somatosensory temporal discrimination threshold is abnormal in patients with cerebellar atrophy. These findings suggest that the cerebellum plays a role in modulating the somatosensory temporal discrimination threshold and confirm the role of cerebellum in the processing of time in the millisecond range.

Background and purpose Charcot-Marie-Tooth disease (CMT) type 1A is characterized by uniformly reduced nerve conduction velocity (NCV) that is fully penetrant since the first years of life, remains fairly stable through the life and does not correlate with disability whereas compound muscular action potential (CMAP) amplitude does. The aim of the present study was to analyze the large amount of electrophysiological data collected in the ascorbic acid trial in Italy and the UK (CMT-TRIAAL/CMT-TRAUK) and to use these data to gain insights into the pathophysiology of NCV in CMT1A. Methods Baseline electrophysiological data from 271 patients were analysed. Electrophysiological recordings were taken from the motor ulnar, median and peroneal nerves and the sensory ulnar nerve. Distal motor latency (DML), motor (MNCV) and sensory (SNCV) nerve conduction velocity, and amplitudes of CMAPs and sensory action potentials were assessed. Electrophysiological findings were correlated with age of patients at examination and the Charcot–Marie−Tooth Examination Score (CMTES). Results NCV was markedly and uniformly reduced. CMAP amplitudes were overall reduced but more severely in lower limbs. DML decreased and MNCV and SNCV increased with age of the patients, whereas CMAP amplitudes worsened with age and also correlated with CMTES. Conclusions This is the largest sample of electrophysiological data obtained so far from CMT1A patients. Axonal degeneration as assessed by means of CMAP amplitude reflected clinical impairment and was consistent with a slowly progressive length-dependent neuropathy. All patients typically had markedly slowed NCV that did, however, slightly increase with age of the patients. The improvement of NCV might depend on myelin thickness remodelling that occurs during the adult life of CMT1A patients.

Background and purpose Quantification of intraepidermal nerve fibers (IENFs) in skin biopsies is now the tool of choice to diagnose small fiber neuropathies. An adequate normative dataset, necessary to assess normality cutoffs, is available for brightfield microscopy but not for immunofluorescence. Methods Intraepidermal nerve fiber density data in distal leg skin samples processed with immunofluorescence were collected from 528 healthy individuals from four experienced laboratories worldwide. In all laboratories skin samples were collected, processed and analyzed according to standard procedures. Quantile regression analysis was employed to tailor the fit of the 5° percentile as the normal cutoff value and to test and measure the effect of age, gender, body mass index, race, biopsy site (lateral distal lower leg or medial posterior mid-calf) and participating laboratory as possible influential variables. Results Age, gender and biopsy site showed an independent linear correlation with IENF density. For each decade the 5° quantile IENF cutoff showed a 0.54 fibers/mm decrease, whilst females exhibited a 1.0 fiber/mm cutoff greater than males. Compared to the lateral distal lower leg, biopsies from the calf showed a 3.4 fibers/mm lower 5° percentile cutoff, documenting a variation linked by site. Conclusions An age- and gender-adjusted normative dataset for IENF density at the lateral distal lower leg obtained with indirect immunofluorescence is presented for the first time by sharing data from four experienced laboratories worldwide. This dataset can be used as reference for laboratories processing skin biopsies with this technique.

RATIONALE: It has been reported that epicardial adipose tissue (EAT) may affect myocardial autonomic function. OBJECTIVE: The aim of this study was to explore the relationship between EAT and cardiac sympathetic nerve activity in heart failure (HF) patients. METHODS AND RESULTS: In 110 patients with systolic HF, we evaluated the correlation between echocardiographic EAT thickness and cardiac adrenergic nerve activity assessed by 123I-metaiodobenzylguanidine (123I-MIBG). The predictive value of EAT thickness on cardiac sympathetic denervation [123I-MIBG early and late heart to mediastinum ratio (H/M) and SPECT total defect score (TDS)] was tested in a multivariate analysis. Furthermore, catecholamine levels, catecholamine biosynthetic enzymes and sympathetic nerve fibers were measured in EAT and subcutaneous adipose tissue (SCAT) biopsies obtained from HF patients who underwent cardiac surgery. EAT thickness correlated with 123I-MIBG early and late H/M and SPECT TDS, but not with left ventricular ejection fraction (LVEF). Moreover, EAT resulted as an independent predictor of 123I-MIBG early and late H/M and SPECT TDS, and showed a significant additive predictive value on 123I-MIBG planar and SPECT results over demographic and clinical data. Although no differences were found in sympathetic innervation between EAT and SCAT, EAT showed an enhanced adrenergic activity demonstrated by the increased catecholamine levels and expression of catecholamine biosynthetic enzymes. CONCLUSIONS: This study provides the first evidence of a direct correlation between increased EAT thickness and cardiac sympathetic denervation in HF.

Background and purpose Charcot−Marie−Tooth disease (CMT) is a very slowly progressive neuropathy which makes it difficult to detect disease progression over time and to assess intervention efficacy. Experience from completed clinical trials with ascorbic acid and natural history studies confirm difficulties in detecting such changes. Consequently, sensitive-to-change outcome measures (OMs) are urgently needed. Methods The relative responsiveness of clinical scales of the Italian−UK ascorbic acid trial (placebo arm) were assessed by using the standardized response mean (SRM), which is the ratio of the paired scores mean change over time to the standard deviation of the score change (0 is worst responsiveness). Results Little worsening of OM scores was found over 2 years. In detail, the primary OM of the trial, the CMT Neuropathy Score version 1 (CMTNSv1), showed low responsiveness (SRM 0.13). Some CMTNS items showed slightly greater responsiveness (CMT Examination Score 0.17; CMTNS Signs 0.19). Myometric assessments of handgrip and foot dorsiflexion strength were the most responsive (SRM −0.31 and −0.38, respectively). Amongst the other measures, the nine-hole peg test, which assesses upper limb functioning, showed the best sensitivity to change (SRM 0.28). Conclusions Overall these OMs showed low or negligible responsiveness, confirming the need to improve current OMs and to develop novel ones for prognostic and interventional studies. However, handgrip and foot dorsiflexion myometry are worth retaining for future trials as they were the most responsive and are likely to be clinically relevant for patients.

We describe the first Italian family affected by CMT2B carrying a Val162Met substitution in the RAB7 gene. The clinical and electrophysiological features of our family are similar to those of previously reported families with RAB7 mutations, also for the higher occurrence of ulcers in males. However, in this family we evaluated the autonomic nervous system, never investigated in CMT2B, by means of skin biopsy and sudomotor and cardiovascular tests. Our findings provide both pathological and functional evidence of autonomic nervous system involvement in CMT2B and expand the phenotypic characterization of CMT2B disease.

We report the clinical, electrophysiological, and skin biopsy findings of an Italian Charcot-Marie-Tooth disease type 2 (CMT2) family with a novel heterozygous GDAP1 mutation. We observed a marked intra-familial phenotypic variability, in age at onset and disease severity which ranged from a typical CMT phenotype to an asymptomatic status. Electrophysiological study, consistent with an axonal sensory-motor neuropathy, confirmed a different degree of severity and disclosed minimal electrophysiological abnormalities also in the asymptomatic subjects. Skin biopsy findings showed a variable loss of large and small somatic nerve fibers. Molecular analysis identified a novel heterozygous missense mutation (Arg120Gly) in the GDAP1 gene which co-segregated with the disease within the pedigree. In conclusion, our findings confirm that the GDAP1 autosomal dominant mutations underlie a pronounced phenotypic variability, mimicking the effects of reduced penetrance. Notably, electrophysiological study in this family allowed to reveal hidden positive family history and assess a dominant inheritance pattern, revealing subclinical neuropathy in asymptomatic mutation carriers.

Introduction: Cold-induced sweating syndrome (CISS) is a rare autosomal recessive disorder caused by mutations in the CRLF1 or CLCF1 genes. It involves paradoxical sweating at cold ambient temperatures on the upper part of the body, along with craniofacial and skeletal features as progressive scoliosis. Mutations in LIFR (leukemia inhibitory factor receptor) responsible for the Stüve-Wiedemann syndrome (STWS), lead to a phenotype resembling CISS, with cold-induced sweating, scoliosis and cubitus valgus, but with a more severe clinical course. In fact, STWS is characterized by bowing of the long bones, respiratory distress, feeding difficulties, and hypertermic episodes responsible for early lethality. Materials and methods: We report clinical, molecular, skin biopsy, electrophysiological and temperature monitoring data of a 30-year-old Italian woman who has suffered from a cold-induced sweating and progressive scoliosis by the age of about 4 years. Results: Clinical data and the course showed a predominant CISS phenotype. Thermoregulatory sweat tests confirmed this paradoxical sweating response. There was clinical and electrophysiological evidence of a mild sensorimotor peripheral neuropathy. The morpho-functional study of cutaneous innervation showed a defective development of cutaneous sympathetic innervation with a lack of immunohistochemical shift from a noradrenergic to cholinergic phenotype. DNA sequencing showed homozygosity for a novel missense sequence variant, c2170> G in LIFR on 5p13-p12. Genome wide SNP arrays including parental samples revealed a complete maternal isodisomy for chromosome 5. Conclusions: Here, we report longitudinal observations on clinical consequences of LIFR dysfunction in a patient with a CISS-like phenotype.

Summary Background Ascorbic acid reduced the severity of neuropathy in transgenic mice overexpressing peripheral myelin protein 22 ( PMP22 ), a model of Charcot–Marie–Tooth disease type 1A (CMT1A) associated with the PMP22 duplication. However, in three 1-year trials, ascorbic acid had no benefit in human beings. We did a multicentre 2-year trial to test the efficacy and tolerability of ascorbic acid in patients with CMT1A. Methods Adult patients (aged 18–70 years) with symptomatic CMT1A were enrolled from nine centres in Italy and the UK, and were randomly assigned (1:1 ratio) to receive 1·5 g/day oral ascorbic acid or matching placebo for 24 months. The randomisation sequence was computer generated by block randomisation, stratified by centre and disease severity, and patients were allocated to treatment by telephone. The primary outcome was change in the CMT neuropathy score (CMTNS) at 24 months. Secondary outcomes were timed 10 m walk test, nine-hole peg test, overall neuropathy limitations scale, distal maximal voluntary isometric contraction, visual analogue scales for pain and fatigue, 36-item short-form questionnaire, and electrophysiological measurements. Patients, treating physicians, and physicians assessing outcome measures were masked to treatment allocation. Analysis of the primary outcome was done on all randomised patients who received at least one dose of study drug. This study is registered, numbers ISRCTN61074476 (CMT-TRAUK) and EudraCT 2006-000032-27 (CMT-TRIAAL). Findings We enrolled and randomly assigned 277 patients, of whom six (four assigned to receive ascorbic acid) withdrew consent before receiving treatment; 138 receiving ascorbic acid and 133 receiving placebo were eligible for analysis. Treatment was well tolerated: 241 of 271 patients (89% in each group) completed the study; 20 patients (nine receiving ascorbic acid) dropped out because of adverse events. Mean CMTNS at baseline with missing data imputed was 14·7 (SD 4·8) in the ascorbic acid group and 13·9 (4·2) in the placebo group. Mean worsening of CMTNS was 0·2 (SD 2·8, 95% CI −0·3 to 0·7) in the ascorbic acid group and 0·2 (2·7, −0·2 to 0·7) in the placebo group (mean difference 0·0, 95% CI −0·6 to 0·7; p=0·93). We recorded no differences between the groups for the secondary outcomes at 24 months. 21 serious adverse events occurred in 20 patients, eight in the ascorbic acid group and 13 in the placebo group. Interpretation Ascorbic acid supplementation had no significant effect on neuropathy compared with placebo after 2 years, suggesting that no evidence is available to support treatment with ascorbic acid in adults with CMT1A. Funding Telethon-UILDM and AIFA (Italian Medicines Agency) for CMT-TRI AA L, and Muscular Dystrophy Campaign for CMT-TRAUK.

BACKGROUND: In overwork weakness (OW), muscles are increasingly weakened by exercise, work or daily activities. Although it is a well-established phenomenon in several neuromuscular disorders, it is debated whether it occurs in Charcot-Marie-Tooth disease (CMT). Dominant limb muscles undergo a heavier overload than non-dominant and therefore if OW occurs we would expect them to become weaker. Four previous studies, comparing dominant and non-dominant hand strength in CMT series employing manual testing or myometry, gave contradictory results. Moreover, none of them examined the behaviour of lower limb muscles. METHODS: We tested the OW hypothesis in 271 CMT1A adult patients by comparing bilateral intrinsic hand and leg muscle strength with manual testing as well as manual dexterity. RESULTS: We found no significant difference between sides for the strength of first dorsal interosseous, abductor pollicis brevis, anterior tibialis and triceps surae. Dominant side muscles did not become weaker than non-dominant with increasing age and disease severity (assessed with the CMT Neuropathy Score); in fact, the dominant triceps surae was slightly stronger than the non-dominant with increasing age and disease severity. DISCUSSION: Our data does not support the OW hypothesis and the consequent harmful effect of exercise in patients with CMT1A. Physical activity should be encouraged, and rehabilitation remains the most effective treatment for CMT patients. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.