VMA21 deficiency prevents vacuolar ATPase assembly and causes autophagic vacuolar myopathy.

X-linked Myopathy with Excessive Autophagy (XMEA) is a childhood onset disease characterized by progressive vacuolation and atrophy of skeletal muscle. We show that XMEA is caused by hypomorphic alleles of the VMA21 gene, that VMA21 is the diverged human ortholog of the yeast Vma21p protein, and that like Vma21p, VMA21 is an essential assembly chaperone of the vacuolar ATPase (V-ATPase), the principal mammalian proton pump complex. Decreased VMA21 raises lysosomal pH which reduces lysosomal degradative ability and blocks autophagy. This reduces cellular free amino acids which leads to downregulation of the mTORC1 pathway, and consequent increased macroautophagy resulting in proliferation of large and ineffective autolysosomes that engulf sections of cytoplasm, merge, and vacuolate the cell. Our results uncover a novel mechanism of disease, namely macroautophagic overcompensation leading to cell vacuolation and tissue atrophy.

Correlation of clinicoserologic and pathologic classifications of inflammatory myopathies: study of 178 cases and guidelines for diagnosis.

The idiopathic inflammatory myopathies (IIM) are acquired muscle diseases characterized by muscle weakness and inflammation on muscle biopsy. Clinicoserologic classifications do not take muscle histology into account to distinguish the subsets of IIM. Our objective was to determine the pathologic features of each serologic subset of IIM and to correlate muscle biopsy results with the clinicoserologic classification defined by Troyanov et al, and with the final diagnoses. We retrospectively studied a cohort of 178 patients with clinicopathologic features suggestive of IIM with the exclusion of inclusion body myositis. At the end of follow-up, 156 of 178 cases were still categorized as IIM: pure dermatomyositis, n = 44; pure polymyositis, n = 14; overlap myositis, n = 68; necrotizing autoimmune myopathy, n = 8; cancer-associated myositis, n = 18; and unclassified IIM, n = 4. The diagnosis of IIM was ruled out in the 22 remaining cases. Pathologic dermatomyositis was the most frequent histologic picture in all serologic subsets of IIM, with the exception of patients with anti-Ku or anti-SRP autoantibodies, suggesting that it supports the histologic diagnosis of pure dermatomyositis, but also myositis of connective tissue diseases and cancer-associated myositis. Unspecified myositis was the second most frequent histologic pattern. It frequently correlated with overlap myositis, especially with anti-Ku or anti-PM-Scl autoantibodies. Pathologic polymyositis was rare and more frequently correlated with myositis mimickers than true polymyositis. The current study shows that clinicoserologic and pathologic data are complementary and must be taken into account when classifying patients with IIM patients. We propose guidelines for diagnosis according to both clinicoserologic and pathologic classifications, to be used in clinical practice.

Nemaline myopathy caused by mutations in the nebulin gene may present as a distal myopathy.

Mutations in the nebulin gene are the main cause of autosomal recessive nemaline myopathy, with clinical presentations ranging from mild to severe disease. We have previously reported a nonspecific distal myopathy caused by homozygous missense mutations in the nebulin gene in six Finnish patients from four different families. Here we describe three non-Finnish patients in two unrelated families with distal nemaline myopathy caused by four different compound heterozygous nebulin mutations, only one of which is a missense mutation. One of the mutations has previously been identified in one family with the severe form of nemaline myopathy. We conclude that nemaline myopathy and distal myopathy caused by nebulin mutations form a clinical and histological continuum. Nemaline myopathy should be considered as a differential diagnosis in patients presenting with an early-onset predominantly distal myopathy.

Non-lethal neonatal neuromuscular variant of glycogenosis type IV with novel GBE1 mutations.

We report a recent case of the severe congenital variant of glycogen storage disease type IV with prolonged survival. The patient was found to be a compound heterozygote for two novel mutations, a missense mutation in exon 5 (p.H188P, c.563A>C) and a severe mutation in intron 5 (c.691+2T>C). We propose that the genotype and the quality of medical care may account for the severe but non-lethal phenotype.

A TPM3 mutation causing cap myopathy.

Cap disease is a rare congenital myopathy associated with skeletal malformations and respiratory involvement. Abnormally arranged myofibrils taking the appearance of a "cap" are the morphological hallmark of this entity. We report a case of cap disease concerning a 42-year-old man, without any family history and presenting a p.Arg168His mutation on the TPM3 gene. His first biopsy at 7years had only shown selective type I hypotrophy. Mutations of TPM3 gene have been found in nemaline myopathy, congenital fiber type disproportion, but never before in cap disease.

Analysis of the DYSF mutational spectrum in a large cohort of patients.

Dysferlinopathies belong to the heterogeneous group of autosomal recessive muscular dystrophies. Mutations in the gene encoding dysferlin (DYSF) lead to distinct phenotypes, mainly Limb Girdle Muscular Dystrophy type 2B (LGMD2B) and Miyoshi myopathy (MM). Here, we analysed the mutational data from the largest cohort described to date, a cohort of 134 patients, included based on clinical suspicion of primary dysferlinopathy and/or dysferlin protein deficiency identified on muscle biopsy samples. Data were compiled from 38 patients previously screened for mutations in our laboratory (Nguyen, et al., 2005; Nguyen, et al., 2007), and 96 supplementary patients screened for DYSF mutations using genomic DHPLC analysis, and subsequent sequencing of detected variants, in a routine diagnostic setting. In 89 (66%) out of 134 patients, molecular analysis identified two disease causing mutations, confirming the diagnosis of primary Dysferlinopathy on a genetic basis. Furthermore, one mutation was identified in 30 patients, without identification of a second deleterious allele. We are currently developing complementary analysis for patients in whom only one or no disease-causing allele could be identified using the genomic screening procedure. Altogether, 64 novel mutations have been identified in this cohort, which corresponds to approximately 25% of all DYSF mutations reported to date. The mutational spectrum of this cohort significantly shows a higher proportion of nonsense mutations, but a lower proportion of deleterious missense changes as compared to previous series. (c) 2008 Wiley-Liss, Inc.

Type 2 myotonic dystrophy can be predicted by the combination of type 2 muscle fiber central nucleation and scattered atrophy.

The diagnosis of Type 2 myotonic dystrophy (DM2/proximal myotonic myopathy) is often overlooked because of a nonspecific clinical presentation and muscle biopsy findings of a "denervation-like" pattern of unknown specificity that combines increased fiber size variation, central nucleation, small angulated fibers, Type 2 fiber atrophy, and nuclear clumps. We determined the presence of these features in 104 patients designated as having an unidentified myopathy from a series of 2,100 muscle biopsies. Because CCUG expansions form pathogenic ribonuclear accumulations that can be detected by in situ hybridization, we validated and then used automated (CCUG)8 in situ hybridization as a reference standard to evaluate the value of each histologic feature for DM2 detection, identifying 8 DM2-positive and 96 DM2-negative cases. Multivariate analyses identified the combination of Type 2 fiber atrophy and central nucleation as the most predictive of DM2 (sensitivity, 1.0; specificity, 0.92). These features were mutually exclusive in non-DM2 patients (p < 0.0001). The relevance of this combination of features was confirmed in an additional independent series (15 DM2-positive vs 17 DM2-negative). Further investigation revealed that central nucleation selectively affects Type 2 fibers in DM2 and, conversely, that it affects Type 1 fibers in DM1 (p < 0.0001). These results will facilitate the routine detection of DM2 and further support the concept that DM2 has a distinct pathophysiology involving type 2 myofibers.

[Limbic encephalitis--evolving concepts]. / L'encéphalite limbique--evolution des concepts.

Limbic encephalitis is an inflammatory disease localized to the "grand lobe limbique" defined by Broca in 1878, sometimes restricted to the hippocampus, but sometimes including extralimbic abnormalities. The main features are subacute onset, short-term memory disorders and cognitive impairment, temporal seizures, and hippocampic changes on MRI. A list of underlying causes has recently been published Infectious causes used to be frequent (mainly herpes simplex virus). Paraneoplastic limbic encephalitis is characterized by the presence of various onconeural antibodies, such as AntiHu and ANNA3 (bronchial small cell carcinoma), AntiMa2 (testicular tumor), AntiCV2 (lymphoma, thymoma,...). No such antibodies are detected in 40% of patients. The prognosis of these forms is poor. Voltage-gated potassium channel-associated limbic encephalopathies are due to antibodies targeting potassium channels. Mutations of the genes encoding the Kv11 and Kv12 subunits are responsible for several Shaker syndromes, including neuromyotonia, Morvan's disease, type I episodic ataxia, and limbic encephalitis with hyponatremia. Plasma exchanges and immunotherapy are effective. In patients without detectable antibodies, hippocampic anti-neuropil antibodies should be sought, particularly those targeting N-methyl-D-aspartate receptors. Ovarian teratoma is the usual cause of this type of encephalitis. Surgery and immunotherapy are effective. These disorders have been categorized into those associated with antibodies targeting intracellular antigens (poor-prognosis paraneoplastic encephalitis) and those associated with antibodies targeting antigens reacting with cellular membranes (potassium channelopathies and antineuropil antibodies), which respond to immunotherapy and carry a better prognosis. Limbic encephalitis can also reveal Hodgkin's disease, as in a case observed by the authors.

Molecular characterization of myophosphorylase deficiency (McArdle disease) in 34 patients from Southern France: identification of 10 new mutations. Absence of genotype-phenotype correlation.

We report on 31 patients and 3 affected siblings (17 males and 17 females) from Southern France with McArdle disease (two from Spanish and three from Portuguese background). Molecular analysis revealed the presence of five previously described mutations: the common p.R50X nonsense mutation, the p.R94W and p.V456M missense mutations, the p.K609K conservative mutation which generates an aberrant splicing, and the p.K754fs frameshift mutation; and 10 new molecular defects: eight missense mutations at homozygous (p.G136D) or heterozygous state (p.T379M, p.G449R, p.T488I, p.R490Q, p.R570Q, p.R590H, and p.R715W), one nonsense mutation p.R650X and one deletion (p.delK170). Our results confirm that the p.R50X nonsense mutation is also the most common associated with myophosphorylase deficiency in the Southern French population: 21 of 25 French unrelated patients (15 homozygous and six heterozygous, i.e., 72% of the mutated alleles). Two patients, one from Algeria and one from Tunisia, were homozygous for a previously identified missense mutation p.V456M in a Moroccan subject. Our findings further demonstrate molecular heterogeneity of myophosphorylase deficiency, absence of genotype-phenotype correlation and expand the already crowded map of mutations within the myophosphorylase gene. Our study also provides evidence for increased medical interest of malignant hyperthermia susceptibility (MHS) because of 34 McArdle disease patients, three and two affected siblings were contracture-tested and found to be positive.

Block of neural Kv1.1 potassium channels for neuroinflammatory disease therapy.

OBJECTIVE: We asked whether blockade of voltage-gated K+ channel Kv1.1, whose altered axonal localization during myelin insult and remyelination may disturb nerve conduction, treats experimental autoimmune encephalomyelitis (EAE). METHODS: Electrophysiological, cell proliferation, cytokine secretion, immunohistochemical, clinical, brain magnetic resonance imaging, and spectroscopy studies assessed the effects of a selective blocker of Kv1.1, BgK-F6A, on neurons and immune cells in vitro and on EAE-induced neurological deficits and brain lesions in Lewis rats. RESULTS: BgK-F6A increased the frequency of miniature excitatory postsynaptic currents in neurons and did not affect T-cell activation. EAE was characterized by ventriculomegaly, decreased apparent diffusion coefficient, and decreased (phosphocreatine + beta-adenosine triphosphate)/inorganic phosphate ratio. Reduced apparent diffusion coefficient and impaired energy metabolism indicate astrocytic edema. Intracerebroventricularly BgK-F6A-treated rats showed attenuated clinical EAE with unexpectedly reduced ventriculomegaly and preserved apparent diffusion coefficient values and (phosphocreatine + beta-adenosine triphosphate)/inorganic phosphate ratio. Thus, under BgK-F6A treatment, brain damage was dramatically reduced and energy metabolism maintained. INTERPRETATION: Kv1.1 blockade may target neurons and astrocytes, and modulate neuronal activity and neural cell volume, which may partly account for the attenuation of the neurological deficits. We propose that Kv1.1 blockade has a broad therapeutic potential in neuroinflammatory diseases (multiple sclerosis, stroke, and trauma).

Platelet-endothelial cell adhesion molecule-1 and CD146: soluble levels and in situ expression of cellular adhesion molecules implicated in the cohesion of endothelial cells in idiopathic inflammatory myopathies.

OBJECTIVE: Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of diseases characterized by chronic inflammation of muscles. We investigated the role of cellular adhesion molecules implicated in the cohesion of endothelial cells in IIM. METHODS: In 22 patients with IIM we investigated plasma concentrations of soluble junctional adhesion molecules [platelet-endothelial cell adhesion molecule (sPECAM-1) and sCD146] and cellular adhesion molecules [sP-selectin, sE-selectin, intercellular adhesion molecule (sICAM-1), and vascular cell adhesion molecule (sVCAM-1)] implicated in leukocyte/endothelial cell interactions. Results were compared to a control group. Muscle biopsy samples from 8 out of 22 IIM patients were studied by immunohistochemistry for tissue expression of these molecules and compared to normal muscle samples. PECAM-1 and CD146 expression was also studied using immunoblots from muscle biopsies from 5 patients and 2 controls. RESULTS: We observed distinct patterns of soluble levels and in situ expression between dermatomyositis (DM), polymyositis (PM), and sporadic inclusion body myositis (s-IBM). PM samples showed significantly increased levels of sCD146, sPECAM-1, and s-ICAM1 and increased expression of CD146, CD31, and ICAM-1 in endothelial cells, whereas CD146 and ICAM-1 were also recorded in some muscle fibers. In DM, sE-selectin, sP-selectin, and sPECAM-1 were significantly increased, with abnormal expression of ICAM-1 in endothelial cells and perifascicular muscle fibers. In the small group of s-IBM samples, results were similar to PM, but the only significant increase was the level of sPECAM-1. Immunoblots confirmed increased expression of PECAM-1 and CD146 in all IIM muscles in comparison to controls, with the highest expression in PM and IBM samples. CONCLUSION: We observed abnormal increases of soluble levels of adhesion molecules implicated in endothelial cell junctions in PM (sCD146, sPECAM-1) and to a lesser extent in DM and s-IBM (sPECAM-1). We conclude that the distinctly different profiles between PM/s-IBM and DM reflect differences in the pathophysiological background of these diseases.

Lewis-Sumner syndrome and multifocal motor neuropathy.

We compared the clinical, electrophysiological, laboratory, and pathological features of 13 patients with Lewis-Sumner syndrome (LSS) with those of 20 patients with multifocal motor neuropathy (MMN). LSS and MMN patients have several common clinical features: age at onset, weakness in the distribution of individual peripheral nerves, mild wasting, cramps and fasciculations, partial areflexia, and frequent stepwise disease course. Cerebrospinal fluid protein level was normal or slightly elevated, but always less than 100 mg/dl. Conduction blocks are the electrophysiological hallmarks of these two neuropathies, and no differences in distribution and number of blocks were found. Contrary to MMN, lower-limb involvement at onset was frequent in LSS but extension to the upper limbs was a frequent later feature of the disease. Cranial nerve involvement was noted in 4 LSS patients during relapses and absent in all MMN patients. The major distinguishing features were the clinical and electrophysiological sensory involvement in LSS, and the lack of anti-GM1 antibodies in LSS, whereas IgM anti-GM1 were found in 40% of MMN patients. Some LSS patients responded to steroid therapy, whereas this was ineffective in MMN. From these features, LSS can be considered an entity distinct from MMN, with its own clinical, laboratory, and electrophysiological characteristics, and as an intermediate link between chronic inflammatory demyelinating polyneuropathy and MMN.

Pellagra: a rare disease observed in a victim of mental and physical abuse.

Lesions of the brain stem and cerebellum due to nutritional deficiencies are mostly seen in chronic alcohol abuse and more rarely in severe malnutrition. We report the case of a 27-year-old woman, found dead in the family flat. She presented cachexia (167 cm, 25 kg) and multiple hematomas of the limbs. Postmortem examination revealed lesions due to peritonitis. Neuropathological examination showed severe atrophy of the corpus callosum and central neuronal chromatolysis, which are observed in pellagra. Inflammatory colitis or celiac disease was not found. Toxicological analysis was negative, in particular no alcohol absorption. Pellagra, which is due to nicotinamide deficiency, is a disease rarely seen in this country. In this case, nutritional deficiency was the consequence of failure to eat in a context of abuse. The woman was born of an incestuous relationship and presented intellectual retardation due to poor affective relations with her mother.

Combination of histopathological and electromyographic patterns can help to evaluate functional outcome of critical ill patients with neuromuscular weakness syndromes.

INTRODUCTION: The aim of the study was to describe patterns of neuromuscular weakness using a combination of electromyography and histology, and to evaluate functional outcome in patients following complicated cardiovascular surgery. METHODS: Fifteen adults requiring long-term mechanical ventilation (>15 days) following cardiovascular surgery associated with postoperative complications were prospectively included. Electrophysiological and histological analyses (muscle and nerve) were performed when failure to wean from mechanical ventilation associated with peripheral neuromuscular weakness was noticed. Functional disability was evaluated 12 months after surgery. RESULTS: Six patients had a predominantly axonal neuropathy, six presented with myopathy, and three patients had a combination of axonal neuropathy and myopathy. All of them presented with acute tetraparesis and failure to wean from mechanical ventilation. All of the study patients who received corticosteroids exhibited a myopathic pattern (with or without axonopathic changes) but never an axonopathic pattern only. Only two of the eight survivors at 12 months were not ambulatory. These two patients had no detectable compound muscle action potential on electrophysiological examination. CONCLUSION: The combination of electromyographic evaluation and neuromuscular histological abnormalities could help to identify the type and severity of neuromuscular weakness, in turn helping to evaluate the patient's potential functional prognosis.

Ascorbic acid treatment corrects the phenotype of a mouse model of Charcot-Marie-Tooth disease.

Charcot-Marie-Tooth disease (CMT) is the most common hereditary peripheral neuropathy, affecting 1 in 2,500 people. The only treatment currently available is rehabilitation or corrective surgery. The most frequent form of the disease, CMT-1A, involves abnormal myelination of the peripheral nerves. Here we used a mouse model of CMT-1A to test the ability of ascorbic acid, a known promoter of myelination, to correct the CMT-1A phenotype. Ascorbic acid treatment resulted in substantial amelioration of the CMT-1A phenotype, and reduced the expression of PMP22 to a level below what is necessary to induce the disease phenotype. As ascorbic acid has already been approved by the FDA for other clinical indications, it offers an immediate therapeutic possibility for patients with the disease.

Focal myositis associated with S-1 radiculopathy: report of two cases.

Two cases are described of pseudotumoral calf hypertrophy after laminectomy for a compressive S-1 radiculopathy. The serum creatine kinase (CK) level was normal or mildly elevated. T2-weighted magnetic resonance imaging (MRI) showed calf enlargement, with an increased signal of the medial head of the gastrocnemius muscle. Electromyography revealed fibrillation potentials and positive sharp waves, but no complex repetitive discharges in the affected gastrocnemius muscle, with motor unit potentials having mixed neurogenic and myopathic features. Muscle biopsy revealed a focal myositis associated with some features of denervation. A brief course of corticosteroids was followed by remission clinically and improvement in the MRI findings.

Multiminicore disease in a family susceptible to malignant hyperthermia: histology, in vitro contracture tests, and genetic characterization.

BACKGROUND: Histological anomalies associated with malignant hyperthermia (MH) have been scarcely reported. In some patients susceptible to MH (MHS), central cores have been identified and a genetic association has been proposed, but multiminicore lesions have not been systematically reported. OBJECTIVE: To analyze the association between multiminicores and MHS in a large family with MH with an approach combining histology, in vitro contracture tests, and genetic analysis. PATIENTS AND METHODS: Twenty-nine members of an MH family (147 members) were investigated. MAIN OUTCOME MEASURES: Muscle biopsy specimens were analyzed histologically and with in vitro contracture tests. Genetic analyses were performed to determine the presence of mutations in the ryanodine receptor (RYR1) gene. RESULTS: According to the gold standard in vitro contracture tests, 17 patients were diagnosed as having MHS and 10 as not being susceptible. Multiminicores were found in 16 of the 17 MHS patients and in a single nonsusceptible participant. A linkage between the MH trait and the RYR1 locus in chromosome 19 was demonstrated, whereas no already known mutations were found. Two missense heterozygous mutations (R2676W and T2787S) were identified from sequencing of the entire coding complementary DNA. Overall, we found a significant association between MHS and the presence of multiminicores (chi(2) = 26.5, P<.001) on the one hand and the presence of new mutations in the RYR1 gene (chi(2) = 19.0, P<.001) on the other hand. This remarkably high occurrence of multiminicores in an MHS family is uncommon, and genetic analyses indicate that the association between multiminicores and MHS is linked to a novel R2656W and T2787S substitution present on the same allele of the RYR1 gene. CONCLUSIONS: These results indicate that multiminicore lesions are observed in MHS patients with neither clinical signs related to multiminicore disease nor histological features of congenital myopathies. These multiminicore lesions may be secondary to mutations in the RYR1 gene. As a consequence, these patients must be distinguished from patients with multiminicore disease and from other MHS patients for whom multiminicores are not observed.

[BK virus-induced tubulo-interstitial nephritis in a renal transplant recipient]. / Néphrite tubulo-interstitielle à virus BK chez un transplanté rénal.

We present a case of renal BK virus infection with renal allograft dysfunction. Renal allograft biopsy showed mononuclear infiltrates in the interstitium and viral inclusions in the tubular epithelial cells. Infected cells were stained with an anti-polyomavirus antibody. The polymerase chain reaction (PCR) performed on blood, urine, and on the DNA extracted from renal tissue showed the presence of the BK virus DNA sequence. The immunosuppressive therapy including tacrolimus, prednisone, and mycophenolate mofetil was reduced leading to an improvement of the renal function. BK virus infection is now recognized as a cause of renal allograft dysfunction, and has been observed with increasing frequency in recent years. Reactivation of the latent virus occurs in immunocompromised hosts such as organ recipients with immunosuppressive treatment. Histologically, renal BK virus infection is characterized by a lymphocytic interstitial infiltrate, and could mimic acute rejection. The pathologist should diagnose the viral infection and may be helped by urine cytology and immunohistochemistry. An accurate diagnosis is important because antirejection therapy favors the decline of the renal function. Enhanced new immunotherapy protocols seem to be the main risk factor for this infection. The response to reduced immunosuppression is variable with reports of an end stage renal failure in 70% of the patients after 18 months.