Introduction
Fatty‐acid oxidation disorders (FAODs) are recessive genetic diseases.
Materials and methods
We report here clinical and paraclinical data from a retrospective study of 44 adults with ...muscular FAODs from six French reference centers for neuromuscular or metabolic diseases.
Results
The study cohort consisted of 44 adult patients: 14 with carnitine palmitoyl transferase 2 deficiency (32%), nine with multiple acyl‐CoA deficiency (20%), 13 with very long‐chain acyl‐CoA dehydrogenase deficiency (30%), three with long‐chain 3‐hydroxyacyl‐CoA dehydrogenase deficiency (7%), and five with short‐chain acyl‐CoA dehydrogenase deficiency (11%). Disease onset occurred during childhood in the majority of patients (59%), with a mean age at onset of 15 years (range = 0.5–35) and a mean of 12.6 years (range = 0–58) from disease onset to diagnosis. The principal symptoms were acute muscle manifestations (rhabdomyolysis, exercise intolerance, myalgia), sometimes associated with permanent muscle weakness. Episodes of rhabdomyolysis were frequent (84%), with a mean creatinine kinase level of 68,958 U/L (range = 660–300,000). General metabolic complications were observed in 58% of patients, respiratory manifestations in 18% of cases, and cardiological manifestations in 9% of cases. Fasting acylcarnitine profile was used to orient genetic explorations in 65% of cases. After a mean follow‐up of 10 years, 33% of patients were asymptomatic and 56% continued to display symptoms after exercise. The frequency of rhabdomyolysis decreased after diagnosis in 64% of cases.
Conclusion
A standardized register would complete this cohort description of muscular forms of FAODs with exhaustive data, making it possible to assess the efficacy of therapeutic protocols in real‐life conditions and during the long‐term follow‐up of patients.
MORC2 gene encodes a ubiquitously expressed nuclear protein involved in chromatin remodeling, DNA repair, and transcriptional regulation. Heterozygous mutations in MORC2 gene have been associated ...with a spectrum of disorders affecting the peripheral nervous system such as Charcot‐Marie‐Tooth (CMT2Z), spinal muscular atrophy‐like with or without cerebellar involvement, and a developmental syndrome associated with impaired growth, craniofacial dysmorphism and axonal neuropathy (DIGFAN syndrome). Such variability in clinical manifestations associated with the increasing number of variants of unknown significance detected by next‐generation sequencing constitutes a serious diagnostic challenge. Here we report the characterization of an in vitro model to evaluate the pathogenicity of variants of unknown significance based on MORC2 overexpression in a neuroblastoma cell line SH‐EP or cortical neurons. Likewise, we show that MORC2 mutants affect survival and trigger apoptosis over time in SH‐EP cell line. Furthermore, overexpression in primary cortical neurons increases apoptotic cell death and decreases neurite outgrowth. Altogether, these approaches establish the pathogenicity of two new variants p.Gly444Arg and p.His446Gln in three patients from two families. These new mutations in MORC2 gene are associated with autosomal dominant CMT and with adult late onset proximal motor neuropathy, further increasing the spectrum of clinical manifestations associated with MORC2 mutations.
Expanding the phenotypic variability of MORC2 gene mutations: From Charcot‐Marie‐Tooth disease to late‐onset pure motor neuropathy
Inflammatory myopathies (IM), characterized by muscle inflammation and weakness, are rare systemic diseases. Our previous study estimated an IM incidence rate of 7.98 cases per million people per ...year (95% confidence interval 7.38-8.66) and highlighted important variations that were likely because of methodologic issues rather than true epidemiologic differences. In this study, we aimed to refine the incidence of IM, using the 2017 European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) classification criteria for IM and a quadruple-source capture-recapture method during a 6-year period in Alsace, France, a region with a population of 2 million having benefits of good access to health care and accredited IM referral centers.
Clinical data of potential IM patients were obtained from 4 sources (general practitioners and community specialists, public and private hospital records, public and private laboratories, and archives from the pathology department). Patients residing in Alsace and who fulfilled the 2017 EULAR/ACR criteria for IM between January 1, 2006, and January 1, 2013, were included. We corrected potentially incomplete ascertainment of cases with capture-recapture analyses. We studied both spatial and temporal distributions of incidence of IM. We also assessed systemic manifestations of the disease.
Our review of 1,742 potential cases identified 106 patients with IM. No spatial or temporal heterogeneity was observed. Use of log-linear models showed an estimated 14.9 additional missed cases. Thus, the incidence rate of IM was 8.22 new cases per million inhabitants per year (95% confidence interval 6.76-9.69). Extramuscular manifestations other than dermatomyositis rash were frequently recorded.
The stringent methodology used in our study provides an accurate estimation of the incidence of IM. This study also demonstrates, in a population-based cohort, the systemic nature of IM.
The objective was to investigate whether resveratrol (RSV) can improve exercise capacity in patients with fatty acid oxidation (FAO) disorders. The study was a randomized, double‐blind, cross‐over ...trial. Nine patients with very long‐chain acyl‐CoA dehydrogenase (VLCAD) deficiency or carnitine palmitoyl transferase (CPT) II deficiency were randomized to receive either 8 weeks of 1000 mg day−1 RSV or placebo (P) followed by a 4‐weeks wash‐out period and subsequently 8 weeks of the opposite treatment. Primary outcome measures were heart rate and FAO as measured via stable isotope technique during constant workload exercise. Secondary outcome measures included fat and glucose metabolism; perceived exertion; as well as subjective measures of energy expenditure, fatigue, and daily function. Eight participants completed the trial. Heart rate did not differ at the end of exercise after treatment with RSV vs placebo (P = .063). Rate of oxidation of palmitate at end of exercise was not different with 1.5 ± 0.8 (RSV) vs 1.3 ± 0.6 (P) μmol kg−1 min−1 (P = .109). Secondary outcomes did not change except for increased plasma glycerol and decreased plasma glucose levels at the end of exercise after treatment with RSV vs placebo. A daily dose of 1000 mg resveratrol does not improve exercise capacity or FAO during exercise in patients with CPTII or VLCAD deficiencies.
Background
The recent lockdown due to the COVID-19 pandemic has been linked to a higher incidence of psychiatric manifestations and substance abuse. The recreative use of nitrous oxide is more and ...more widespread and neurological complications are frequent.
Methods
We report clinical characteristics and biological findings of five consecutive patients presenting to our tertiary care center between April 2020 and February 2021 with various neurological symptoms occurring after recent nitrous oxide abuse.
Results
Our patients presented with subacute combined degeneration of the spinal cord (4/5 patients) or with acute inflammatory demyelinating polyneuropathy (1/5 patients). No patient had reduced vitamin B-12 titer, but all had elevated blood levels of homocysteine and methylmalonic acid. This reflects the functional deficit in vitamin B-12 that can be linked to nitrous oxide consumption. After vitamin B-12 supplementation, clinical signs regressed at least partially in all 5 patients.
Conclusion
We report an elevated incidence of neurological complications of nitrous oxide abuse occurring during the recent COVID-19 lockdown. Nitrous oxide abuse should be tracked down in patients presenting with compatible neurological symptoms and elevated homocysteinemia. Vitamin B-12 should be supplemented as soon as the diagnosis is made.
X-Linked Charcot-Marie-Tooth disease type 1 (CMTX1) is characterized by gender differences in clinical severity. Women are usually clinically affected later and less severely than men. However, their ...clinical presentation appears to be heterogenous. Our aim was to extend the phenotypic description in a large series of women with CMTX1.
We retrospectively evaluated 263 patients with CMTX1 from 11 French reference centers. Demographic, clinical, and nerve conduction data were collected. The severity was assessed by CMT Examination Score (CMTES) and Overall Neuropathy Limitations Scale (ONLS) scores. We looked for asymmetrical strength, heterogeneous motor nerve conduction velocity (MNCV), and motor conduction blocks (CB).
The study included 137 women and 126 men from 151 families. Women had significantly more asymmetric motor deficits and MNCV than men. Women with an age of onset after 19 years were milder. Two groups of women were identified after 48 years of age. The first group represented 55%, with women progressing as severely as men, however, with a later onset age. The second group had mild or no symptoms. Some 39% of women had motor CB. Four women received intravenous immunoglobulin before being diagnosed with CMTX1.
We identified two subgroups of women with CMTX1 who were over 48 years of age. Additionally, we have demonstrated that women with CMTX can exhibit an atypical clinical presentation, which may result in misdiagnosis. Therefore, in women presenting with chronic neuropathy, the presence of clinical asymmetry, heterogeneous MNCV, and/or motor CB should raise suspicion for X-linked CMT, particularly CMTX1, and be included in the differential diagnosis.
The tapering of prednisone therapy in generalized myasthenia gravis (MG) presents a therapeutic dilemma; however, the recommended regimen has not yet been validated.
To compare the efficacy of the ...standard slow-tapering regimen of prednisone therapy with a rapid-tapering regimen.
From June 1, 2009, to July 31, 2013, a multicenter, parallel, single-blind randomized trial was conducted to compare 2 regimens of prednisone tapering. Data analysis was conducted from February 18, 2019, to January 23, 2020. A total of 2291 adults with a confirmed diagnosis of moderate to severe generalized MG at 7 specialized centers in France were assessed for eligibility.
The slow-tapering arm included a gradual increase of the prednisone dose to 1.5 mg/kg every other day and a slow decrease once minimal manifestation status of MG was attained. The rapid-tapering arm consisted of immediate high-dose daily administration of prednisone, 0.75 mg/kg, followed by an earlier and rapid decrease once improved MG status was attained. Azathioprine, up to a maximum dose of 3 mg/kg/d, was prescribed for all participants.
The primary outcome was attainment of minimal manifestation status of MG without prednisone at 12 months and without clinical relapse at 15 months. Intention-to-treat analysis was conducted.
Of the 2291 patients assessed, 2086 did not fulfill the inclusion criteria, 87 declined to participate, and 1 patient registered after trial closure. A total of 117 patients (58 in the slow-tapering arm and 59 in the rapid-tapering arm) were selected for inclusion by MG specialists and were randomized. The population included 62 men (53%); median age was 65 years (interquartile range, 35-69 years). The proportion of patients having met the primary outcome was higher in the rapid- vs slow-tapering arm (23 39% vs 5 9%), with a risk ratio of 3.61 (95% CI, 1.64-7.97; P < .001) after adjusting for center and thymectomy. The rapid-tapering regimen allowed sparing of a mean of 1898 mg (95% CI, -3121 to -461 mg) of prednisone over 1 year (ie, 5.3 mg/d per patient, P = .03). The number of serious adverse events did not differ significantly between the slow- vs rapid-tapering group (13 22% vs 21 36%, P = .15).
In patients with moderate to severe generalized MG who require high-dose prednisone with azathioprine therapy, rapid tapering of prednisone appears to be feasible, well tolerated, and associated with a good outcome.
ClinicalTrials.gov Identifier: NCT00987116.
Background and purpose
Biallelic variants in SORD have been reported as one of the main recessive causes for hereditary peripheral neuropathies such as Charcot–Marie–Tooth disease type 2 (CMT2) and ...distal hereditary motor neuropathy (dHMN) resulting in lower limb (LL) weakness and muscular atrophy. In this study, phenotype and genotype landscapes of SORD‐related peripheral neuropathies were described in a French and Swiss cohort. Serum sorbitol dosages were used to classify SORD variants.
Methods
Patients followed at neuromuscular reference centres in France and Switzerland were ascertained. Sanger sequencing and next generation sequencing were performed to sequence SORD, and mass spectrometry was used to measure patients' serum sorbitol.
Results
Thirty patients had SORD peripheral neuropathy associating LL weakness with muscular atrophy, foot deformities (87%), and sometimes proximal LL weakness (20%) or distal upper limb weakness (50%). Eighteen had dHMN, nine had CMT2, and three had intermediate CMT. Most of them had a mild or moderate disease severity. Sixteen carried a homozygous c.757delG (p.Ala253Glnfs*27) variant, and 11 carried compound heterozygous variants, among which four variants were not yet reported: c.403C > G, c.379G > A, c.68_100 + 1dup, and c.850dup. Two unrelated patients with different origins carried a homozygous c.458C > A variant, and one patient carried a new homozygous c.786 + 5G > A variant. Mean serum sorbitol levels were 17.01 mg/L ± 8.9 SD for patients carrying SORD variants.
Conclusions
This SORD‐inherited peripheral neuropathy cohort of 30 patients showed homogeneous clinical presentation and systematically elevated sorbitol levels (22‐fold) compared to controls, with both diagnostic and potential therapeutic implications.
Background
To describe the clinical, pathological, and molecular characteristics of late‐onset (LO) dysferlinopathy patients.
Methods
Retrospective series of patients with LO dysferlinopathy, defined ...by an age at onset of symptoms ≥30 years, from neuromuscular centers in France and the International Clinical Outcome Study for dysferlinopathy (COS). Patients with early‐onset (EO) dysferlinopathy (<30 years) were randomly selected from the COS study as a control group, and the North Star Assessment for Dysferlinopathy (NSAD) and Activity Limitation (ACTIVLIM) scores were used to assess functionality. Muscle biopsies obtained from 11 LO and 11 EO patients were revisited.
Results
Forty‐eight patients with LO dysferlinopathy were included (28 females). Median age at onset of symptoms was 37 (range 30–57) years and most patients showed a limb‐girdle (n = 26) or distal (n = 10) phenotype. However, compared with EO dysferlinopathy patients (n = 48), LO patients more frequently showed atypical phenotypes (7 vs. 1; p = 0.014), including camptocormia, lower creatine kinase levels (2855 vs. 4394 U/L; p = 0.01), and higher NSAD (p = 0.008) and ACTIVLIM scores (p = 0.016). Loss of ambulation in LO patients tended to occur later (23 ± 4.4 years after disease onset vs. 16.3 ± 6.8 years; p = 0.064). Muscle biopsy of LO patients more frequently showed an atypical pattern (unspecific myopathic changes) as well as significantly less necrosis regeneration and inflammation. Although LO patients more frequently showed missense variants (39.8% vs. 23.9%; p = 0.021), no differences in dysferlin protein expression were found on Western blot.
Conclusions
Late‐onset dysferlinopathy patients show a higher frequency of atypical presentations, are less severely affected, and show milder dystrophic changes in muscle biopsy.
Late‐onset dysferlinopathy patients show a higher frequency of atypical presentations, including camptocormia, and are less severely affected compared with early‐onset patients. Furthermore, they present less necrosis and inflammation in muscle biopsy.
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