PubMed Health⌕ Search

Biomedical subjects

J M Vallat

Publications and source records attributed to J M Vallat.

At least 19 recordsLinked to original sources
PubMed2006

Spine deformities in Charcot-Marie-Tooth 4C caused by SH3TC2 gene mutations.

BACKGROUND: Charcot-Marie-Tooth (CMT) disease is a heterogeneous group of inherited peripheral motor and sensory neuropathies with several modes of inheritance: autosomal dominant, X-linked, and autosomal recessive (AR) CMT. A locus responsible for the demyelinating form of ARCMT was assigned to the 5q23-q33 region (CMT4C) by homozygosity mapping. Recently, 11 mutations were identified in the SH3TC2 (KIAA1985) gene in 12 families with demyelinating ARCMT from Turkish, Iranian, Greek, Italian, or German origin. OBJECTIVE: To identify mutations in the SH3TC2 gene. METHODS: The authors searched for SH3TC2 gene mutations in 10 consanguineous CMT families putatively linked to the CMT4C locus on the basis of haplotype segregation and linkage analysis. RESULTS: Ten families had mutations, eight of which were new and one, R954X, recurrent. Six of the 10 mutations were in exon 11. Onset occurred between ages 2 and 10. Scoliosis or kyphoscoliosis and foot deformities were found in almost all patients and were often inaugural. The median motor nerve conduction velocity values (</=34 m/s) were not correlated with disease duration. The functional disability score was </=3, indicating that the patients could walk without help. Unexpectedly, typical giant axons were observed on biopsies from a large Algerian family. CONCLUSIONS: Charcot-Marie-Tooth type 4C (CMT4C) is less severe than other autosomal recessive (AR) CMT. Intrafamilial variability is important, making phenotype-genotype correlations difficult, but spine deformities are clearly a hallmark of CMT4C. In the presence of scoliosis, a neurologic examination is recommended. Giant axons on biopsies are also suggestive of CMT4C. For genetic analysis, the R954X mutation should be looked for before systematic sequencing of exon 11.

Charcot-Marie-Tooth Disease↗
PubMed2006

[Polyneuropathy involving cranial nerves associated with monoclonal IgM antibodies with anti-MAG/SGPG/SGPLG/sulfatides activity].

INTRODUCTION: A typically distal and symmetrical, slowly progressive sensorimotor demyelinating neuropathy is caused by monoclonal IgM against myelin-associated glycoprotein (MAG) and SGPG, SGLPG glycolipids in the context of a benign IgM paraproteinemia. We studied a patient with a neuropathy that fulfilled the diagnostic criteria for CIDP in whom IgM kappa anti-MAG/SGPG/SGLPG were detected. OBSERVATION: The patient was a 57-year-old man who had developed a slowly progressive distal sensorimotor neuropathy, involving the lower then upper limbs, with cranial nerves palsies (oro-pharyngo-laryngo territory). ENMG showed a demyelinating neuropathy with a disproportionate slowing of conduction in distal segments of motor and axonal features in the lower limbs. The first routine laboratory analysis revealed negative or normal findings. Several serum protein electrophoreses were normal. The third cerebrospinal fluid examination demonstrated a moderate and late rise in CSF protein level with no cells. Monoclonal IgM-kappa against MAG/SGPG/SGLPG, was detected; anti-MAG antibody titre in the serum was 20 059 BTU (N<1000). A small IgM-kappa paraprotein was identified by immunofixation. Electron microscopy failed to show nerve fibers with widening of outer lamellae of the myelin. There is no clinical improvement after different treatments, immunoglobulins IV, cortisteroids, plasma exchange, rituximab. CONCLUSION: It is not known whether this neuropathy is an atypical form of PNMAG or an CIDP associated with anti-MAG. When ENMG show a disproportionate slowing of conduction in distal segments of motor nerves, one should screen the serum with immunofixation to identify small monoclonal components. If IgM-MGUS is present, search should be undertaken for anti-MAG/SGPG/SGLPG antibodies. Diagnosis enables optimal treatment using, in severe cases, expensive current strategies with immunoglobulins IV, plasma exchange, and corticosteroids, or, in the event of no response, rituximab before resorting to more toxic drugs like cyclophosphamide.

Antibodies, Anti-Idiotypic↗
PubMed2005

[Chronic inflammatory demyelinating polyradiculoneuropathy: diagnostic strategy. Guidelines of the French CIDP study group].

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) comprises a group of dysimmune neuropathies easily diagnosed in more than half of the patients. Diagnosis is based on clinical, electrophysiological and biological clues. In some patients, diagnosis is unclear because of the debated value of the available clues. In such circumstances, dysimmune neuropathies may not be diagnosed, leading to insufficient treatment. This is an important category of patients because immunomodulatory drugs have proven efficacy. The CIDP spectrum includes a relatively wide range of diseases. Besides the easily recognized classic forms, there are many clinical variants, sometimes with a paucisymptomatic presentation leading to uncertain diagnosis. The French CIDP study group has established guidelines for diagnostic strategy in CIDP patients. The first part of this paper is devoted to the clinical aspects of the disease, classical forms and variants. In the second part, the results of electrophysiological studies are reported. In a third chapter, complementary examinations useful for diagnosis are discussed. The fourth chapter deals with the diagnostic strategy, discussed in relation to the different situations which may be encountered in clinical practice. details the technical modalities of appropriate electrophysiological studies and presents normal results together with those indicating demyelinating neuropathy. Nerve biopsy technique and results are given in appendix II.

Humans↗
PubMed2004

Demyelinating peripheral neuropathy associated with hemophagocytic lymphohistiocytosis. An immuno-electron microscopic study.

We report the case of an 11-year-old male who developed subacute diffuse polyradiculoneuropathy, associated with digestive symptoms and Epstein-Barr virus infection. Parental consanguinity was present. The laboratory findings including bone marrow smear were consistent with hemophagocytic lymphohistiocytosis (HLH). Electrophysiological study of peripheral nerves revealed an intense and diffuse demyelinating process. The histological nerve lesions were severe and purely demyelinating. Most axons were intact. There was a diffuse infiltration of the nerve parenchyma by mononuclear cells. Immuno-electron microscopic study evidenced entry of macrophages into Schwann cell cytoplasm with dissociation of myelin sheaths. This boy died several months after the onset of the neuropathic symptoms. HLH is a rare genetic or acquired disorder in childhood characterized by abnormal immune activation, which induces an uncontrolled inflammatory response with sustained hyperactivation of T lymphocytes and macrophages. Only very rare cases of peripheral nerve involvement have been described in HLH. This is the first case showing that peripheral nerves, as other viscera, may be destroyed by the macrophagic infiltration, which characterizes HLH.

Child↗
PubMed2004

Autosomal recessive forms of Charcot-Marie-Tooth disease.

In some countries with a high prevalence of consanguineous marriages, autosomal recessive inheritance is likely to account for the great majority of all forms of Charcot-Marie-Tooth (CMT) disease. As with the dominant forms, it is usual to differentiate the demyelinating forms (autosomal recessive -CMT1 or AR-CMT4) from the axonal forms (AR-CMT2). Genetic analysis of large families with recessive transmission has proved to be an efficient mean of discovering novel CMT genotypes (eg, the genes GDAP1, MTMR2, MTMR13, KIAA1985, NDGR1, periaxin, and lamin). Because of the clinical, electrophysiologic, and histologic heterogeneity of these patients, it is likely that there are numerous genes that remain to be discovered, which will probably make classification even more complex. Clinical, and especially histologic, phenotypes often lead to a suspicion that a specific gene is implicated. There is, therefore, an indication for nerve biopsy to orient diagnostic research in molecular biology, which is presently very time consuming and can only be performed in highly specialized laboratories.

Adult↗
PubMed2003

Phenotypic variability in autosomal recessive axonal Charcot-Marie-Tooth disease due to the R298C mutation in lamin A/C.

Autosomal recessive forms of axonal Charcot-Marie-Tooth (ARCMT2) disease are frequent in some areas, such as North Africa and the Middle East, since consanguineous marriages are still common there. Recently, a unique homozygous mutation in LMNA, which encodes lamin A/C, a component of the nuclear envelope, was identified in members of three Algerian families with ARCMT2 linked to chromosome 1q21.2-q21.3. In the present study we describe a group of 21 ARCMT2 patients from seven unrelated Algerian families with the same R298C mutation in the lamin A/C gene and marked variability of the clinical phenotype. There is a wide range of age of onset, from 6 to 27 years, with a mean of 14.4 +/- 4.6 years. The course of the disease varies considerably from one patient to another. Twelve patients with a disease duration of 10-15 years had a severe CMT phenotype with distal wasting and weakness of all four limbs and areflexia associated with involvement of the proximal lower limb muscles. In contrast, nine patients had the classical CMT phenotype with mild functional disability without proximal lower limb involvement after a disease duration of 5-18 years. Electrophysiological studies showed a median motor nerve conduction velocity (MNCV) in the normal range in almost all the patients. MNCV and compound muscle action potential (CMAP) values were inversely correlated with the disease duration and the MNCV was strictly related to the CMAP, strongly supporting a pure axonal process without a demyelinating component. Six patients had a nerve biopsy, which revealed severe rarefaction of myelinated fibres in all cases and an increased density of unmyelinated fibres in the majority of cases. In conclusion, the ARCMT2 associated with the R298C mutation differs from other types of ARCMT2. The variability among patients in the age of onset and the course of the disease strongly suggests the action of modifying genes, which remain to be identified.

Adolescent↗
PubMed2003

Identification of seven novel mutations in the GAN gene.

Giant axonal neuropathy (GAN) is a severe early onset neurodegenerative disorder affecting both the peripheral nerves and the central nervous system. The diagnosis is based on the presence of characteristic giant axons on nerve biopsy. In GAN, the integrity of the intermediate filament network is altered. Indeed, abnormal accumulation of the intermediate filaments has been reported in different cell types, including in the swollen axons, which are filled with neurofilaments. We identified the defective protein, gigaxonin, of unknown function, and reported fourteen distinct mutations in twelve families of various origins. Two additional mutations have been recently reported. In the present study, we analysed the GAN gene in 6 families, and identified seven novel mutations: three nonsense and two missense mutations and two deletions. In addition, the molecular result for an already reported family was re-evaluated. In this family, the R269Q "polymorphism" is in fact the pathogenic mutation.

Age of Onset↗
PubMed2003

The phenotypic manifestations of autosomal recessive axonal Charcot-Marie-Tooth due to a mutation in Lamin A/C gene.

Charcot-Marie-Tooth disease constitutes a genetically heterogeneous group of hereditary motor and sensory peripheral neuropathies. The axonal type of Charcot-Marie-Tooth is designated type 2. Six loci for autosomal dominant and three for recessive Charcot-Marie-Tooth type 2 have been reported so far. In this study we report the phenotype of autosomal recessive axonal Charcot-Marie-Tooth type 2 due to a recently-described mutation (c.892C>T-p.R298C) in a gene encoding Lamin A/C nuclear envelope proteins and the first gene in which a mutation leads to autosomal recessive Charcot-Marie-Tooth type 2. We have explored eight patients from four Algerian families. The onset is usually in the second decade and the course is rapid, involving upper limbs and proximal muscles, leading to a severe condition in less than 4 years. Many different mutations in Lamin A/C have been identified as causing variable phenotypes, such as limb girdle muscular dystrophy type 1B, autosomal dominant and recessive Emery-Dreyfuss muscular dystrophy, dilated cardiomyopathy with atrioventricular conduction defect, and Dunnigan-type familial partial lipodystrophy should prompt us to fully investigate the skeletal and cardiac muscles in patients affected with autosomal recessive Charcot-Marie-Tooth type 2 carrying a mutation in LMNA.

Algeria↗
PubMed2002

Genetic heterogeneity in giant axonal neuropathy: an Algerian family not linked to chromosome 16q24.1.

Giant axonal neuropathy is a rare severe autosomal recessive childhood disorder affecting both the peripheral nerves and the central nervous system. Peripheral nerves characteristically show giant axonal swellings filled with neurofilaments. The giant axonal neuropathy gene was localised by homozygosity mapping to chromosome 16q24.1 and identified as encoding a novel, ubiquitously expressed cytoskeletal protein named gigaxonin.We describe a consanguineous Algerian family with three affected sibs aged 16, 14 and 12 years who present a mild demyelinating sensory motor neuropathy, hypoacousia and kyphoscoliosis which was moderate in the two elder patients, severe in the third one, with no sign of central nervous system involvement and normal cerebral magnetic resonance imaging. This clinical picture is different from the classical severe form, with kinky hairs and early onset of central nervous system involvement and from the less severe form, with protracted course and late involvement of central nervous system. Nerve biopsy showed a moderate loss of myelinated fibers and several giant axons with thin or absent myelin, filled with neurofilaments. This neuropathological aspect is similar to the previously described families linked to the gigaxonin gene. Genetic study in this family showed absence of linkage to chromosome 16q24.1, indicating for the first time, a genetic heterogeneity in giant axonal neuropathy. We propose to call this form of giant axonal neuropathy giant axonal neuropathy 2, and to use the name of giant axonal neuropathy 1 for the form linked to 16q24.1.

Adolescent↗
PubMed2002

[Nerve biopsy].

Explore the source record for details and available documents.

Biopsy↗
PubMed2002

[Hashimoto's encephalitis].

Hashimoto's encephalitis was first described more than 30 years ago. The clinical picture is typically that of a subacute encephalopathy with a moderate to marked alteration of consciousness, seizures, myoclonus or tremulousness. Additional stroke-like episodes can occur along the course of the disease which may be monophasic or relapsing. The diagnosis of Hashimoto's encephalitis requires the presence of an elevated titer of antithyroid antibodies (mainly anti-thyroperoxidase and also anti-thyroglobulin) which is not necessarily associated with obvious thyroid dysfunction. The results of neurologic investigations are not specific and show typically a global slowing of the EEG, a moderately high CSF protein content and a normal or near normal imaging except in rare cases. The disorder is considered autoimmune and is remarkably responsive to corticosteroids which must be started as soon as possible after the diagnosis has been confirmed biologically. The long-term prognosis is usually good but some patients may die or present major neurologic sequelae.

Encephalitis↗
PubMed2002

[Chronic polyradiculoneuritis and its frontiers].

The Chronic Inflammatory Demyelinating Polyradiculoneuropathies (CIDP) constitute a syndrome whose incidence is difficult to evaluate, and is probably underestimated. In the course of this presentation, we deliberately restricted discussion to issues raised in recent years concerning the extent of this syndrome. We discuss diagnostic criteria, especially electrophysiological ones. As the criteria proposed by the ad hoc committee of the American Academy of Neurology in 1991 have been questioned due to lack of sensitivity, new ones have been proposed recently. We briefly discuss the different types of chronic dysimmune demyelinating neuropathy: not only the CIDP, but also the Lewis and Sumner syndrome or multifocal inflammatory demyelinating neuropathy and the multiple conduction block neuropathies. At last, we point out the consistent finding of axonal involvement in the course of a chronic demyelinating neuropathy; over time, it can become pre-dominant, which may make diagnosis difficult by suggesting a chronic axonal neuropathy that may be assumed to be primary. Consideration of these points may help clinicians recognize more chronic dysimmune neuropathies, for which immunosuppressive therapy has been found to be effective.

Anti-Inflammatory Agents↗
PubMed2001

Protein zero is necessary for E-cadherin-mediated adherens junction formation in Schwann cells.

Protein Zero (P0), the major structural protein in the peripheral nervous system (PNS) myelin, acts as a homotypic adhesion molecule and is thought to mediate compaction of adjacent wraps of myelin membrane. E-Cadherin, a calcium-dependent adhesion molecule, is also expressed in myelinating Schwann cells in the PNS and is involved in forming adherens junctions between adjacent loops of membrane at the paranode. To determine the relationship, if any, between P0-mediated and cadherin-mediated adhesion during myelination, we investigated the expression of E-cadherin and its binding partner, beta-catenin, in sciatic nerve of mice lacking P0 (P0(-/-)). We find that in P0(-/-) peripheral myelin neither E-cadherin nor beta-catenin are localized to paranodes, but are instead found in small puncta throughout the Schwann cell. In addition, only occasional, often rudimentary, adherens junctions are formed. Analysis of E-cadherin and beta-catenin expression during nerve development demonstrates that E-cadherin and beta-catenin are localized to the paranodal region after the onset of myelin compaction. Interestingly, axoglial junction formation is normal in P0(-/-) nerve. Taken together, these data demonstrate that P0 is necessary for the formation of adherens junctions but not axoglial junctions in myelinating Schwann cells.

Adherens Junctions↗
PubMed2001

Pathological findings in the x-linked form of Charcot-Marie-Tooth disease: a morphometric and ultrastructural analysis.

Mutations in the connexin 32 gene (Cx 32) are associated with the x-linked form of Charcot-Marie-Tooth disease (CMTX) and segregate with a CMT 1 phenotype. The gap junction protein Cx 32 is expressed in myelinating Schwann cells and has been localized to regions of non-compacted cytoplasm in paranodes and in Schmidt-Lanterman incisures. Mutant Cx 32 myelin proteins are predicted to impair Schwann cell functions. We have studied the resulting pathology in motor and sensory nerves from the probands of 13 CMTX kindreds with precisely defined genotype. This report provides a detailed descriptive and morphometric analysis of 14 CMTX nerve biopsy samples, taken at various stages in the development of the neuropathy and studied by light and electron microscopic examination. Findings indicated unusually prominent changes in paranodal myelin with resulting widened nodes of Ranvier, but with segmental demyelination being less common. In parallel early axonal cytoskeletal abnormalities were noted, which were followed later by axonal atrophy, degeneration and loss of myelinated nerve fibers, occurring in a length-dependent fashion. Regenerative sprouting was also unusually prominent. Ultrastructural abnormalities included a frequent dilatation of the adaxonal spaces, prominence of the adaxonal Schwann cell cytoplasm and widening of the Schmidt-Lanterman incisures. We conclude that mutations in Cx 32 gap junction protein lead to a compromise of Schwann cell functions and to impaired Schwann cell-axon interactions with subsequent pathology in both myelin and axons.

Adolescent↗
PubMed2001

[Hashimoto encephalopathy. Analysis of four case reports].

INTRODUCTION: Encephalopathy associated with Hashimoto's thyroiditis has been recognized for more than 30 years and is probably underestimated. EXEGESIS: We report four patients with Hashimoto's thyroiditis who presented neurological or psychiatric features. There were three women and one man, with a mean age of 68 years. Neurological presentations were various: seizures, psychotic episodes, altered consciousness, hallucinations without usual aetiological diseases (infectious, metabolic, neoplasic, vascular, etc.). Neurological investigations (EEG, brain CT, magnetic resonance imaging) were unspecific. In all cases, a moderately high CSF protein level without pleocytosis was found. Patients presented slight hypothyroidism with high titers of antithyroperoxidase antibodies. Despite hormone therapy replacement, neurological features persisted. Outcome was favorable under steroid therapy. CONCLUSION: Hashimoto's encephalopathy must be considered in the face of neuropsychiatric manifestations without obvious etiology. Pathogenic mechanisms are not clear but probably involve autoimmune cerebral vasculitis because of the efficacy of steroids.

Aged↗
PubMed2001

Factors correlated with hypermetabolism in patients with amyotrophic lateral sclerosis.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a severe disease characterized by neurogenic amyotrophy and degeneration of upper and lower motor neurons. Although ALS patients usually experience reductions in fat-free mass (FFM), hypermetabolism via an undetermined source has also been reported. OBJECTIVE: The objective was to clarify the metabolic level of ALS patients. DESIGN: We measured the resting energy expenditure (REE) of 62 patients (32 men and 30 women) with ALS and investigated the factors correlated with metabolic level. Nutritional evaluation included bioelectrical impedance analysis, indirect calorimetry, and calculation of the body mass index. Neurologic assessment included an evaluation of peripheral and central neurologic deficit. Forced vital capacity was measured and smoking status was noted. A complete blood cell count was made and thyroid hormone and C-reactive protein concentrations were measured. RESULTS: Patients were hypermetabolic, by an average of approximately 10% more than in a reference healthy population. FFM, age, and the neutrophil count were significantly associated with REE. The only variable that contributed to the prediction of REE, REE/Z100 kHz (bioimpedance at 100 kHz), REE adjusted for FFM, or the ratio of measured REE to calculated REE was the neutrophil count, which explained only a small percentage of variance in the multiple regression analysis. Hypermetabolism was not associated with a reduction in respiratory function, tobacco use, hyperthyroidism, spasticity and fasciculation intensities, or infection. CONCLUSIONS: Our study corroborates the surprising finding that ALS patients are hypermetabolic. FFM, age, sex, manual muscular testing, the modified Norris limb score, weight, and an increase in circulating neutrophil counts correlated with the hypermetabolic state. Other factors may play a role in pathophysiologic processes that involve mitochondrial energy production or even sympathoadrenergic activation.

Adult↗