Clinical and Molecular Spectrum Associated with COL6A3 c.7447A>G p.(Lys2483Glu) Variant: Elucidating its Role in Collagen VI-related Myopathies.

BACKGROUND: Dominant and recessive autosomal pathogenic variants in the three major genes (COL6A1-A2-A3) encoding the extracellular matrix protein collagen VI underlie a group of myopathies ranging from early-onset severe conditions (Ullrich congenital muscular dystrophy) to milder forms maintaining independent ambulation (Bethlem myopathy). Diagnosis is based on the combination of clinical presentation, muscle MRI, muscle biopsy, analysis of collagen VI secretion, and COL6A1-A2-A3 genetic analysis, the interpretation of which can be challenging. OBJECTIVE: To refine the phenotypical spectrum associated with the frequent COL6A3 missense variant c.7447A>G (p.Lys2483Glu). METHODS: We report the clinical and molecular findings in 16 patients: 12 patients carrying this variant in compound heterozygosity with another COL6A3 variant, and four homozygous patients. RESULTS: Patients carrying this variant in compound heterozygosity with a truncating COL6A3 variant exhibit a phenotype consistent with COL6-related myopathies (COL6-RM), with joint contractures, proximal weakness and skin abnormalities. All remain ambulant in adulthood and only three have mild respiratory involvement. Most show typical muscle MRI findings. In five patients, reduced collagen VI secretion was observed in skin fibroblasts cultures. All tested parents were unaffected heterozygous carriers. Conversely, two out of four homozygous patients did not present with the classical COL6-RM clinical and imaging findings. Collagen VI immunolabelling on cultured fibroblasts revealed rather normal secretion in one and reduced secretion in another. Muscle biopsy from one homozygous patient showed myofibrillar disorganization and rimmed vacuoles. CONCLUSIONS: In light of our results, we postulate that the COL6A3 variant c.7447A>G may act as a modulator of the clinical phenotype. Thus, in patients with a typical COL6-RM phenotype, a second variant must be thoroughly searched for, while for patients with atypical phenotypes further investigations should be conducted to exclude alternative causes. This works expands the clinical and molecular spectrum of COLVI-related myopathies.

Skin Biopsy Findings in Patients With CMT1A: Baseline Data From the CLN-PXT3003-01 Study Provide New Insights Into the Pathophysiology of the Disorder.

Charcot-Marie-Tooth disease type 1A (CMT1A), the most common form of Charcot-Marie-Tooth diseases, is a demyelinating neuropathy caused by a deletion encompassing the gene coding for PMP22, a myelin protein of the peripheral nervous system. Although myelinated fibers are mostly involved in CMT1A, some patients experience neuropathic pain. We thus investigated whether unmyelinated fibers are lost in CMT1A. Skin biopsies were taken from the distal portion of the leg of 80 patients with CMT1A as part of the PXT30003-01 study and processed for quantification of intraepidermal nerve fiber density (IENFD). Mean IENFD was significantly lower in CMT1A patients than in healthy controls. Although the data were highly dispersed, IENFD tended to decrease with age and was higher overall in female patients and controls than male patients and controls. This study shows that small nerve fibers are affected in CMT1A and that this correlates with pin sensitivity. The density of epidermal Langerhans cells (LCs) was also significantly reduced in CMT1A patients, suggesting the involvement of LCs in neuropathic pain processes. These findings raise several questions concerning the interactions of Schwann cells and LCs with unmyelinated fibers in CMT1A. Moreover, they suggest that factors other than PMP22 gene dosage are involved in small fiber pathology in CMT1A.

A novel mutation of the C-terminal amino acid of FUS (Y526C) strengthens FUS gene as the most frequent genetic factor in aggressive juvenile ALS.

Although amyotrophic lateral sclerosis (ALS) typically occurs around 60 years, numerous publications report an onset of ALS before the age of 25 years that define juvenile ALS (jALS). Over the last decade, growing literature mentioned jALS with an aggressive evolution which are mainly linked to the FUS gene. We report here the case of a 25-year-old woman with a bulbar onset ALS that progressed in less than 12 months to invasive ventilation due to respiratory failure; Genetic screening identified a new mutation in the FUS gene that lies within the last codon. After reading the literature, it might be legitimate to consider that jALS linked to FUS mutations represent a specific entity different from both classical jALS and adult ALS linked to FUS gene. This should encourage clinician to firstly screen the FUS gene in the presence of a sporadic ALS that occurs before the age of 25 and with an aggressive profile of evolution.

Punctate pattern: A promising imaging marker for the diagnosis of natalizumab-associated PML.

OBJECTIVE: To evaluate the usefulness of the punctate pattern (PP) for the diagnosis and follow-up of patients with progressive multifocal leukoencephalopathy (PML). METHODS: A cohort of 20 consecutive patients with PML, related to natalizumab (NTZ) (n = 14) or not (n = 6), underwent 3T MRI (147 MRI examinations). MRI was available at presymptomatic (n = 9 patients), symptomatic (n = 15), immune reconstitution inflammatory syndrome (IRIS), and chronic stages (n = 20). A pathologic control group of patients without PML (n = 80), with clinically definitive multiple sclerosis or a clinically isolated syndrome suggestive of CNS demyelination, underwent the same MRI protocol. Number and appearance of punctate lesions were assessed by 3 blinded readers using T2-weighted, fluid-attenuated inversion recovery (FLAIR), and postcontrast T1-weighted images. RESULTS: Interobserver agreement was good (κ = 0.79) (0.72-0.87). Of the 20 patients with PML, 18 had PP, including the 14 patients with NTZ-PML; none in the pathologic control group. Of the 9 presymptomatic patients with NTZ-PML, PP was observed in 7 (78% sensitive and 100% specific). Nonenhancing PP on T2-weighted/FLAIR images was detected in 13 patients with PML, exclusively at the presymptomatic or symptomatic stages (including 7 NTZ-PML), whereas enhancing PP occurred in 16 patients with PML, including 13 of the 14 patients with NTZ-PML at the IRIS stage. CONCLUSIONS: PP is a highly specific feature of PML and may be the first imaging feature at the presymptomatic stage with potential implications in patient care. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that a PP on MRI accurately identifies patients with NTZ-PML.

Punctate and curvilinear gadolinium enhancing lesions in the brain: a practical approach.

INTRODUCTION: Cerebral punctate and curvilinear gadolinium enhancements (PCGE) correspond to opacification of small vessel lumen or its perivascular areas in case of blood-brain barrier (BBB) disruption. We will discuss the possible causes of intra-parenchymal central nervous system PCGE. METHODS: Our review is based on French database including patients presenting with central nervous system PCGE and literature search using PubMed database with the following keywords: punctate enhancement, linear enhancement, and curvilinear enhancement. Disorders which displayed linear leptomeningeal or periventricular enhancements without intra-parenchymal PCGE are excluded of this review. RESULTS: Among our 39 patients with PCGE, 16 different diagnoses were established. After combining our PCGE causes with those described in the literature, we propose a practical approach. Besides physiologic post-contrast enhancement of small vessels, three pathologic conditions may exhibit PCGE: (1) small collateral artery network seen in Moyamoya syndrome, (2) small veins congestions related to developmental or acquired venous outflow disturbance, and (3) disorders causing small vessels BBB disruption indicated by T2 and FLAIR hyperintensities in the corresponding areas of PCGE. Disruption of the BBB could be caused by a direct injury of the endothelial cell, as in posterior reversible encephalopathy syndrome, Susac syndrome, and radiochemotherapy-induced injuries, or by an angiocentric cellular infiltrate, as in inflammatory disorders, demyelinating diseases, host immune responses fighting against infections, prelymphoma states, lymphoma, and in CLIPPERS. CONCLUSION: PCGE may conceal several causes, including physiological and pathological conditions. Nevertheless, a practical approach could improve its management and limit the indications of brain biopsy to very specific situations.

Distinctive Patterns of Transthyretin Amyloid in Salivary Tissue: A Clinicopathologic Study of 92 Patients With Amyloid-containing Minor Salivary Gland Biopsies.

Accurate typing of amyloidosis is still a major issue for pathologists and clinicians. Besides clinical data and immunohistochemistry, the histologic distribution of amyloid could represent a useful tool to prevent typing errors, such as the misdiagnosis of hereditary and senile amyloidosis as light chain-related amyloidosis (AL). Minor salivary gland biopsy (MSGB) is a widely performed procedure for amyloidosis diagnosis and typing. In the largest clinicopathologic series of amyloid-containing MSGB specimens to date, we investigated for the first time whether amyloidosis subtypes can be distinguished according to their pattern of salivary amyloid deposition. The histologic distribution and semiquantification of amyloid within salivary tissue were thoroughly reassessed for each case using Congo red-fluorescence. Clinical data were retrospectively collected. The cohort included 92 patients with amyloid-containing minor salivary gland biopsies. The type of amyloidosis was AL in 51 patients (55.4%), non-V30M mutant ATTR in 10 (10.9%), V30M mutant ATTR in 8 (8.7%), serum amyloid A-derived amyloidosis (AA) in 6 (6.5%), wild-type ATTR in 4 (4.3%), gelsolin in 3 (3.3%), and unclassified in 10 (10.9%). Amyloid was more abundant in AL and AA compared with ATTR amyloidosis, because of more extensive basement membranes and vascular deposits. Conversely, non-V30M mutant ATTR and wt-ATTR were strongly associated with peculiar amyloid nodules located in close contact with salivary excretory ducts, with a specificity of 91.7%. In conclusion, our study suggests for the first time that MSGB, in addition to its high sensitivity for amyloidosis diagnosis, is a simple and effective tool for the recognition of ATTR amyloidosis.

Functional Characterization of a Central Core Disease RyR1 Mutation (p.Y4864H) Associated with Quantitative Defect in RyR1 Protein.

BACKGROUND: Central Core Disease (CCD) is a congenital myopathy often resulting from a mutation in RYR1 gene. Mutations in RyR1 can increase or decrease channel activity, or induce a reduction in the amount of protein. The consequences of a single mutation are sometimes multiple and the analysis of the functional effects is complex. OBJECTIVE: The consequences of the p.Y4864H mutation identified in a CCD patient have been studied regarding both RyR1 function and amount. METHODS: The amount of RyR1 in human and mouse muscles was evaluated using qRT-PCR and quantitative Western blot, and calcium release was studied using calcium imaging on primary cultures. The results were compared between human and mouse. RESULTS: The p.Y4864H mutation induced an alteration of calcium release, and in addition was associated to a reduction in the amount of RyR1 in the patient's muscle. This suggests two possible pathophysiological mechanisms: the alteration of calcium release could result from a modification of the channel properties of RyR1 or from a RyR1 reduction. In order to discriminate between the two hypotheses, we used the heterozygous RyR1 knockout (RyR1+/-) mouse model showing a comparable RyR1 protein reduction. No reduction in calcium release was observed in primary muscle culture from these mice, and no muscle weakness was measured. CONCLUSIONS: Because the reduction in the amount of RyR1 protein has no functional consequences in the murine model, the muscle weakness observed in the patient is most likely the result of a modification of the calcium channel function of RyR1 due to the p.Y4864H mutation.

JC-virus seroconversion in multiple sclerosis patients receiving natalizumab.

AIM: The objectives of this study were to evaluate the rate of JC virus (JCV) seroconversion/seroreversion in a French cohort of multiple sclerosis (MS) patients receiving natalizumab (NTZ), describe the characteristics of this population, identify risk factors for JCV seropositivity and analyse the additional value of quantitative JCV serology results in this context. METHODS: MS patients from two French MS centres, whose JCV serological status in 2011 while receiving NTZ was known (n=357; first-generation enzyme-linked immunosorbent assay (ELISA) test (Gen1)), were proposed for inclusion in this study. We evaluated the rate of JCV seroconversion over a period of one year with a second-generation ELISA test (Gen2; n=303) and analysed the quantitative results. Multivariate analysis was performed to identify risk factors for JCV seropositivity. RESULTS: Among the patients with Gen2 JCV serology (n=303) that had been JCV-seronegative one year before (n=165), the rate of JCV seroconversion was 26.67% (44/165). We observed a higher proportion of anti-JCV antibody seroconverters (14.5%) than expected (≤3%) but also increasing index values of anti-JCV antibody over time. CONCLUSION: Our data suggest that JCV reactivation occurs during NTZ therapy and leads to an increase in the anti-JCV antibodies titre, thus making them more easily detectable by the second-generation ELISA test.

HTLV-1-associated inflammatory myopathies: low proviral load and moderate inflammation in 13 patients from West Indies and West Africa.

BACKGROUND: The Human T-cell Leukemia Virus type 1 (HTLV-1) is the causative agent of several inflammatory diseases, including HTLV-1-associated inflammatory myopathies (HAIM). Little is known about the virological and immunological characteristics of this viral disease. OBJECTIVES: To characterize the histological and virological features of HAIM patients, in order to better understand the pathogenetic mechanisms and unravel new biological markers of this disease. STUDY DESIGN: We conducted a retrospective study on 13 patients with HAIM, based on blood and muscle samples. We included blood samples from HTLV-1-infected individuals without myopathy as controls. Muscle biopsies were used for a broad immunohistological evaluation of tissue damage and inflammation, as well as identification of infected cells through in situ hybridization. DNA extracted from patients' PBMC was used to identify the virus genotype by sequencing and to assess the proviral load by quantitative PCR. Anti-viral antibodies in plasma samples were titrated by indirect immunofluorescence. RESULTS: Patients originate from HTLV-1 endemic areas, the West Indies and West Africa. Histological alterations and inflammation in patients muscles were mostly moderate, with classical features of idiopathic myositis and rare HTLV-1-infected infiltrating cells. In all patients, HTLV-1 belonged to the A subtype, transcontinental subgroup. Anti-HTLV-1 antibodies titers were high, but the proviral load was not elevated compared to asymptomatic HTLV-1 carriers. CONCLUSION: We show here that muscle inflammation is moderate in HAIM, and accompanied by a low HTLV-1 proviral load, suggesting that the pathogenetic events do not exactly mirror those of other HTLV-1-associated inflammatory diseases.

Rituximab in refractory and non-refractory myasthenia: a retrospective multicenter study.

INTRODUCTION: Few data are available about the effect of rituximab (RTX) on refractory (RM) and non-refractory (NRM) myasthenia. METHODS: This retrospective multicenter study involved 13 RM and 7 NRM patients treated with sequential RTX infusions over 2 years, on average. RTX was used as a substitute for corticosteroids in NRM patients. Disability was assessed using the annualized relapse rate (ARR) and Myasthenia Gravis Foundation of America (MGFA) scores. RESULTS: RTX induction decreased the ARR from 2.1 to 0.3 (P < 0.001), and lowered MGFA scores from 5-3b to 4b-0 in RM patients, and from 1.9 to 0.1 (P < 0.001) and 4b-2b to 3b-0 in NRM patients. No side effects were reported in either group, except for 1 case of spondylodiscitis 1 year after the last RTX infusion. Within a year after RTX induction, complete corticosteroid withdrawal was obtained in 7 RM and 4 NRM patients. CONCLUSIONS: RTX is efficacious and well-tolerated. Its use allows for dose reduction or withdrawal of corticosteroids.

Regional difference and similarity of familial amyloidosis with polyneuropathy in France.

Familial amyloidosis with polyneuropathy (FAP) in France have a large genetic heterogeneity with 29 transthyretin (TTR) gene mutations; Met30-TTR is the most frequent one (62%); followed by Tyr77-TTR (11.8%) and Phe77-TTR (6.2%). Analysis of 60 FAP patients diagnosed during the period 2008-2010 showed amyloid polyneuropathy was initially suspected in only 38% patients. TTR Met30 of Portuguese ancestry is different from TTR Met30 of non Portuguese ancestry and other non Met30 variants in geographical distribution and clinical presentation. There are three additional phenotypes of the neuropathy including multifocal upper limbs neuropathy, ataxic polyneuropathy and motor neuropathy. Patients with Tyr77-TTR are characterized by a late onset (>50 years), frequent ataxic phenotype; they are localized mainly in north of France. The more frequent use of the TTR genetic tests and the French network for FAP will help in the future to improve diagnosis and care.

Anti-JCV antibody prevalence in a French cohort of MS patients under natalizumab therapy.

To measure the prevalence of JCV-specific antibodies in a French cohort of MS patients treated with natalizumab and to identify risk factor(s) of JCV seropositivity. Progressive multifocal leukoencephalopathy (PML) risk may be stratified by anti-JCV antibody status, duration of natalizumab therapy (≥24 months) and prior exposure to immunosuppressive (IS) drugs. No data are available in France on the prevalence of anti-JCV antibodies and distribution of PML risk factors in patients treated with natalizumab. Sera of 361 patients under natalizumab therapy in two MS centers were analyzed using a previously validated ELISA test. We studied different characteristics: demographic, ethnic, radiological, clinical, prior use of immunomodulatory (IM) or IS drugs and natalizumab exposure duration. The JCV seropositivity rate was 51 % for the whole cohort. Mean natalizumab exposure duration was 27.27 months ± 15.57 (mean ± SD), and prior use of IS drugs was observed in 15.24 % of patients. Twenty-three patients (6.4 %) presented the three PML risk factors. By multivariate analysis, presence of anti-JCV antibodies was significantly linked to age, North African origin and natalizumab exposure duration. Anti-JCV antibody prevalence was similar to previously published data. Anti-JCV antibody status was linked to age. We also suggested that anti-JCV antibody status could be linked to natalizumab exposure duration and ethnic characteristics.

Effective immune restoration after immunosuppressant discontinuation in a lupus patient presenting progressive multifocal leukoencephalopathy.

Progressive multifocal leukoencephalopathy (PML) is an opportunistic infection of the central nervous system with JC virus. Few cases have been described in lupus patients. We describe biopsy-proven PML in a lupus patient receiving mycophenolate mofetil and corticosteroids. Although the patient received no antiviral treatment, the polymerase chain reaction test for JC virus became negative in cerebrospinal fluid after immunosuppressant discontinuation and the patient survived. We discuss the restoration of immune efficiency after immunosuppressant discontinuation in this case and compare the clinical, radiological and histological features with the inflammatory PML form described in human immunodeficiency virus-infected patients.

Clinical outcome in 19 French and Spanish patients with valosin-containing protein myopathy associated with Paget's disease of bone and frontotemporal dementia.

We report the clinical, histological and genetic findings in 10 families (19 patients) presenting mutations in the valosin-containing protein (VCP). The mean age at onset was 42 years. The clinical pattern was characterized by an early involvement of the proximal upper limbs with scapular winging. Axial and lower limb muscles were often affected, whereas facial, oculobulbar muscles were spared. Ten patients were wheelchair bound after a mean disease course of 9 years and six patients required canes for walking. Two patients required mechanically assisted ventilation and seven patients had reduced vital capacity. There was no cardiac involvement. Paget's disease of bone was observed in eight patients and cognitive impairment in nine patients. Seven patients died as a consequence of weakness and respiratory distress. Muscle biopsy showed rimmed vacuolar myopathy. Genetic analysis revealed missense heterozygous mutations mostly located in exon 5 of the VCP gene, four of which were not previously reported. We observed intrafamilial and interfamilial variability in terms of severity, distribution of weakness and presence or not of Paget's disease or cognitive impairment.