Defects in amphiphysin 2 (BIN1) and triads in several forms of centronuclear myopathies.

Myotubular myopathy and centronuclear myopathies (CNM) are congenital myopathies characterized by generalized muscle weakness and mislocalization of muscle fiber nuclei. Genetically distinct forms exist, and mutations in BIN1 were recently identified in autosomal recessive cases (ARCNM). Amphiphysins have been implicated in membrane remodeling in brain and skeletal muscle. Our objective was to decipher the pathogenetic mechanisms underlying different forms of CNM, with a focus on ARCNM cases. In this study, we compare the histopathological features from patients with X-linked, autosomal recessive, and dominant forms, respectively, mutated in myotubularin (MTM1), amphiphysin 2 (BIN1), and dynamin 2 (DNM2). We further characterize the ultrastructural defects in ARCNM muscles. We demonstrate that the two BIN1 isoforms expressed in skeletal muscle possess the phosphoinositide-binding domain and are specifically targeted to the triads close to the DHPR-RYR1 complex. Cardiac isoforms do not contain this domain, suggesting that splicing of BIN1 regulates its specific function in skeletal muscle. Immunofluorescence analyses of muscles from patients with BIN1 mutations reveal aberrations of BIN1 localization and triad organization. These defects are also observed in X-linked and autosomal dominant forms of CNM and in Mtm1 knockout mice. In addition to previously reported implications of BIN1 in cancer as a tumor suppressor, these findings sustain an important role for BIN1 skeletal muscle isoforms in membrane remodeling and organization of the excitation-contraction machinery. We propose that aberrant BIN1 localization and defects in triad structure are part of a common pathogenetic mechanism shared between the three forms of centronuclear myopathies.

POLG1 variations presenting as multiple sclerosis.

OBJECTIVE: To describe 2 unrelated patients with novel variations in the POLG1 gene and features undistinguishable from multiple sclerosis, ie, optic neuritis, brain white matter hyperintense areas, and unmatched cerebrospinal fluid oligoclonal bands. DESIGN: Case report. SETTING: University hospital. Patients  Both patients subsequently developed bilateral ophthalmoplegia, ptosis, myopathy, cardiomyopathy, ataxia, dysphagia, and hearing and cognitive impairment. MAIN OUTCOME MEASURES: Detailed clinical and laboratory examinations including brain magnetic resonance imaging, morphological analysis of a muscle biopsy, characterization of mitochondrial DNA integrity, sequencing of the POLG1 gene, and screening of control subjects for POLG1 sequence variants. RESULTS: Ragged red fibers and multiple deletions of mitochondrial DNA were detected in the skeletal muscle. Four compound heterozygous variations, including 3 previously unreported, were identified in POLG1. CONCLUSION: Clinicians should be aware of the existence of POLG1-related multiple sclerosis-like illness, as it has important implications for management, treatment, and genetic counseling.

Myopathies in the elderly: a hospital-based study.

Population in western countries is ageing, and myopathies are likely to be more frequently found in elderly patients. We analyzed the files of 270 consecutive adult patients (age >18 years) with newly diagnosed biopsy-proven myopathy in the 2003-2009 interval. Fifty patients (18%) were aged with more than 70 years. In this group of elderly patients, 50% had inflammatory myopathy, 32% had genetically-determined myopathy, 16% had myopathy of unspecified cause, and 2% had toxic myopathy. When considering muscle weakness and serum creatine kinase activity, there was no statistical difference between elderly patients and younger patients. In contrast, elderly patients more frequently presented with myalgia, inflammatory myopathy, and cancer. Myopathies in the elderly are frequent in developed countries, representing a significant proportion of adult myopathies in our series. Muscle pain was a prominent symptom and inflammatory myopathies, often associated with cancer, were the most frequent cause of myopathy. Clinicians should be aware of the existence of geriatric myopathies, an emerging entity with important implications for management, treatment, and genetic counseling.

TDP43-positive intraneuronal inclusions in a patient with motor neuron disease and Parkinson's disease.

BACKGROUND: The role of the 43-kDa transactivation-responsive DNA-binding protein (TDP43) in neurodegenerative diseases is not yet clearly established. OBJECTIVE: To assess for the first time the presence of TDP43 in a patient with motor neuron disease (MND) and Parkinson's disease (PD). METHODS: A 78-year-old woman developed poorly dopa-responsive parkinsonism without cognitive alteration. Three years later, MND appeared and led to death in less than a year. Neuropathologic examination was performed. RESULTS: We observed the presence of PD and MND lesions with TDP43-positive cytoplasmic inclusions in the spinal cord and bulbar nuclei but not in the dentate gyrus and neocortex. The MND was characterized by a severe degeneration of bulbar and cervical lower motor neurons. Numerous senile plaques and topographically limited neurofibrillary tangles were also observed. CONCLUSION: The mechanisms underlying the rare co-occurrence of PD and MND are still unclear. The assessment of an abnormal reactivity for TDP43 in our case might gain more insight into the pathophysiology of this association of two diseases. Further studies are needed to confirm these findings and to understand the role of TDP43 in neurodegenerative diseases.

Muscle phosphorylase b kinase deficiency revisited.

Muscle phosphorylase b kinase (PHK) deficiency (glycogenosis type VIII) is a rare disorder caused by mutations in the PHKA1 gene encoding the alpha(M) subunit of PHK. Only 5 patients with molecular defects in the X-linked PHKA1 gene have been described until now, and they all presented with exercise intolerance. Here, we report a patient with a new mutation in the PHKA1 gene who presented with PHK deficiency, cognitive impairment, but no overt myopathy. This report supports the concept that PHK deficiency is a mild metabolic myopathy and suggests that PHK mutations may interfere with normal brain function.

A novel variation in the Twinkle linker region causing late-onset dementia.

Variations in the mitochondrial helicase Twinkle (PEO1) gene are usually associated with autosomal dominant chronic progressive external ophthalmoplegia (PEO). We describe five patients from two unrelated Alsatian families with the new R374W variation in the Twinkle linker region who progressively developed an autosomal dominant multisystem disorder with PEO, hearing loss, myopathy, dysphagia, dysphonia, sensory neuropathy, and late-onset dementia resembling Alzheimer's disease. These observations demonstrate that Twinkle variations in the linker domain alter cerebral function and further implicate disrupted mitochondrial DNA integrity in the pathogenesis of dementia.

Use of SNP array analysis to identify a novel TRIM32 mutation in limb-girdle muscular dystrophy type 2H.

Molecular diagnosis of monogenic diseases with high genetic heterogeneity is usually challenging. In the case of limb-girdle muscular dystrophy, multiplex Western blot analysis is a very useful initial step, but that often fails to identify the primarily affected protein. We report how homozygosity analysis using a genome-wide SNP array allowed us to solve the diagnostic enigma in a patient with a moderate form of LGMD, born from consanguineous parents. The genome-wide scan performed on the patient's DNA revealed several regions of homozygosity, that were compared to the location of known LGMD genes. One such region indeed contained the TRIM32 gene. This gene was previously found mutated in families with limb-girdle muscular dystrophy type 2H (LGMD2H), a mild autosomal recessive myopathy described in Hutterite populations and in 4 patients with a diagnosis of sarcotubular myopathy. A single missense mutation was found in all these patients, located in a conserved domain of the C-terminal part of the protein. Another missense mutation affecting the N-terminal part of TRIM32, observed in a single consanguineous Bedouin family, was reported to cause the phenotypically unrelated and genetically heterogeneous Bardet-Biedl syndrome, defining the BBS11 locus. Sequencing of TRIM32 in our patient revealed a distal frameshift mutation, c.1753_1766dup14 (p.Ile590Leu fsX38). Together with two recently reported mutations, this novel mutation confirms that integrity of the C-terminal domain of TRIM32 is necessary for muscle maintenance.

Diffusion-weighted MRI of denervated muscle: a clinical and experimental study.

OBJECTIVE: The aim of this study was to investigate skeletal muscle denervation using diffusion-weighted magnetic resonance imaging (DWMRI). MATERIALS AND METHODS: Sciatic nerve axotomy was performed in a group of nine New Zealand White rabbits, and electromyographic (EMG), pathological, and DWMRI studies were conducted on ipsilateral hamstring muscles 1 and 8 days after axotomy. In addition, DWMRI studies were carried out on leg muscles of ten patients with acute and subacute lumbosacral radiculopathy. RESULTS: High intensity signals on short tau inversion recovery (STIR) magnetic resonance imaging and an increased apparent diffusion coefficient (ADC) were observed in denervated muscles of the animals 1 and 8 days after axotomy as well as in denervated muscles of the patients with radiculopathy. In the clinical study, ADC was 1.26 +/- 0.18 x 10(-9) m(2)/s in normal muscle and increased to 1.56 +/- 0.23 x 10(-9) m(2)/s in denervated muscles (p = 0.0016). In animals, EMG and muscle pathological studies were normal 1 day after axotomy, and the muscles demonstrated spontaneous activity on EMG and neurogenic atrophy on histological studies 7 days later. CONCLUSION: This DWMRI study demonstrates that enlargement of extracellular fluid space in muscle denervation is an early phenomenon occurring several days before the appearance of EMG and histological abnormalities.

Percutaneous inoculated rabbit model of intervertebral disc space infection: magnetic resonance imaging features with pathological correlation.

OBJECTIVES: The aims of this study were to characterize MRI features in percutaneously inoculated spondylodiscitis rabbit models, to evaluate MRI for non-invasive diagnosis, and to assess the incremental information brought by the use of gadolinium-enhanced MR sequences. METHODS: Under fluoroscopic control, lumbar discs of 12 New Zealand White adult rabbits were injected with bacterial suspension. Five, 10 and 15 days after bacterial inoculation, T1 and T2 signal abnormalities and contrast enhancement of discs, vertebrae and epidural spaces were evaluated. Bacteriological and pathological analyses were realized after completion of imaging series. RESULTS: Disc space infections were present in all animals. MRI detected vertebral and discal abnormalities as soon as, respectively, 5 and 10 days after inoculation. Gadolinium-enhanced sequences allowed an earlier diagnosis, a more precise evaluation of the extent of the infection and the identification of epidural involvement. The signal of vertebrae was a more reliable criterion for infection evaluation that discal one. CONCLUSIONS: MRI is a reliable tool for non-invasive diagnosis of vertebral infection in a rabbit model and can be useful to compare the efficiency of different antimicrobial therapy in animal series before human administration. Gadolinium-enhanced MR sequences allow an earlier and more precise determination of the presence and extent of infection. Modifications of vertebral signal are the more reliable criterion for the evaluation of disc spaces infection.

Sp3 and sp4 transcription factor levels are increased in brains of patients with Alzheimer's disease.

BACKGROUND/AIMS: Alzheimer's disease (AD) is characterized by extracellular Abeta peptide deposition originating from amyloid precursor protein cleavage and intracellular neurofibrillary tangles resulting from pathological tau protein aggregation. These processes are accompanied by dramatic neuronal losses, further leading to different cognitive impairments. Neuronal death signalings involve gene expression modifications that rely on transcription factor alterations. Herein, we investigated the fate of the Sp family of transcription factors in postmortem brains from patients with AD disease and in different contexts of neuronal death. METHODS/RESULTS: By immunohistochemistry we found that the Sp3 and Sp4 levels were dramatically increased and associated with neurofibrillary tangles and pathological tau presence in neurons from the CA1 region of the hippocampus, as well as the entorhinal cortex of AD patient brains. The Sp transcription factor expression levels were further analyzed in cortical neurons in which death is induced by amyloid precursor protein signaling targeting. While the Sp1 levels remained constant, the Sp4 levels were slightly upregulated in response to the death signal. The Sp3 isoforms were rather degraded. Interestingly, when overexpressed by transfection experiments, the three Sp family members induced neuronal apoptosis, Sp3 and Sp4 being the most potent proapoptotic factors over Sp1. CONCLUSION: Our data evidence Sp3 and Sp4 as new hallmarks of AD in postmortem human brains and further point out that Sp proteins are potential triggers of neuronal death signaling cascades.

Novel Lamp-2 gene mutation and successful treatment with heart transplantation in a large family with Danon disease.

Lysosome-associated membrane protein-2 deficiency (LAMP-2 deficiency), or Danon disease, is a rare X-linked lysosomal disease characterized by cardiomyopathy, vacuolar myopathy, and mental retardation. Less than 20 families with mutations of the Lamp-2 gene have been reported. We describe a family from Sardinia with eight affected patients (4 females and 4 males) and a novel mutation in exon 2 of the Lamp-2 gene (c.102_103delAG). Females developed isolated cardiomyopathy in adulthood, whereas males presented with cardiomyopathy, myopathy, and mental retardation before the age of 20 years. Cardiomyopathy was lethal in three females in their 40s and in three males before the age 20 years. One patient was successfully treated by heart transplantation with more than 5-year follow-up. This study demonstrates that Danon disease is a frequently fatal condition that is potentially treatable with heart transplantation.

A study of three patients with amyotrophic lateral sclerosis and a polyneuropathy resembling CIDP.

We report three patients with a syndrome that fulfilled clinical and laboratory criteria for definite chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) who failed immunosuppressive treatment and eventually developed progressive amyotrophic lateral sclerosis (ALS). Mean disease duration was 23 months (13-38) before death. Two patients had a family history of ALS without mutations of the SOD1 gene. Postmortem examination in one patient showed an endoneurial infiltration of mononuclear cells in lumbar roots and distal and proximal peripheral nerves, mainly around myelinated fibers, with demyelination and axonal loss, consistent with CIDP. The spinal cord revealed severe neuronal loss in the anterior horn, axonal loss in the corticospinal tract, and large numbers of phagocytes in the anterior and lateral tracts, indicative of ALS. Whether demyelinating polyneuropathy was coincident with ALS or was a cause or consequence of motor neuron degeneration in these patients remains to be elucidated. This unusual combination may provide an important clue in elucidating the pathogenesis of ALS in some patients.

Chronic inflammatory demyelinating polyradiculoneuropathy in patients with liver transplantation.

We report two patients with orthotopic liver transplantation (OLT) who developed a syndrome that fulfilled criteria for definite chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). One patient had OLT because of alcoholic cirrhosis and one following hepatitis C-induced hepatic failure. Both had immunosuppressive therapy, with cyclosporine and prednisolone in one case and tacrolimus in the other case. Treatment with intravenous immune globulin (IVIG) significantly improved the neuropathy in both patients. In patients with OLT developing disabling sensorimotor neuropathies, CIDP should be considered as should the use of potentially beneficial immunosuppressive treatment.

Lithostathine quadruple-helical filaments form proteinase K-resistant deposits in Creutzfeldt-Jakob disease.

Autocatalytic cleavage of lithostathine leads to the formation of quadruple-helical fibrils (QHF-litho) that are present in Alzheimer's disease. Here we show that such fibrils also occur in Creutzfeldt-Jakob and Gerstmann-Sträussler-Scheinker diseases, where they form protease-K-resistant deposits and co-localize with amyloid plaques formed from prion protein. Lithostathine does not appear to change its native-like, globular structure during fibril formation. However, we obtained evidence that a cluster of six conserved tryptophans, positioned around a surface loop, could act as a mobile structural element that can be swapped between adjacent protein molecules, thereby enabling the formation of higher order fibril bundles. Despite their association with these clinical amyloid deposits, QHF-litho differ from typical amyloid fibrils in several ways, for example they produce a different infrared spectrum and cannot bind Congo Red, suggesting that they may not represent amyloid structures themselves. Instead, we suggest that lithostathine constitutes a novel component decorating disease-associated amyloid fibrils. Interestingly, [6,6']bibenzothiazolyl-2,2'-diamine, an agent found previously to disrupt aggregates of huntingtin associated with Huntington's disease, can dissociate lithostathine bundles into individual protofilaments. Disrupting QHF-litho fibrils could therefore represent a novel therapeutic strategy to combat clinical amyloidoses.

Polymorphism of the codon 129 of the prion protein (PrP) gene and neuropathology of cerebral ageing.

We studied whether codon 129 polymorphism of the PrP gene modulates the presence of tau- and Abeta-associated lesions among 188 patients over 70 years of age without evidence of dementia. Val allele carriers, either heterozygotes or homozygotes, were more frequently affected by Abeta-associated lesions than non Val allele carriers, whereas there were no differences for tau-positive neurones. Val allele carriers also had more focal and diffuse Abeta deposits. This association was most significant in the highest Braak's stages for neurofibrillary tangles (>/=III). In this group, cases with at least one Val allele had nearly twice as many Abeta-associated lesions. The most affected areas were the entorhinal cortex, TF-TH and the superior temporal cortex, where odds ratios for focal Abeta deposits ranged from 3.5 to 4.6.

Immunohistochemical localization of 14.3.3 zeta protein in amyloid plaques in human spongiform encephalopathies.

The localization of 14.3.3 proteins was studied in different subtypes of brain amyloid plaques. We examined paraffin-embedded brain sections of sporadic MV2 Creutzfeldt-Jakob disease (sCJD) with Kuru plaques, sporadic VV2 CJD with plaque-like PrP(sc) (the abnornal form of prion protein) deposits, variant CJD (vCJD) with florid plaques, Gerstmann-Straüssler-Scheinker (GSS) with multicentric plaques and of Alzheimer's disease (AD) with senile plaques. Adjacent immunostaining revealed PrP(sc) and 14.3.3 zeta deposits in the same amyloid plaques in all cases of sporadic CJD and vCJD, whereas 14.3.3 zeta was not seen in amyloid plaques of GSS with A117V, P102L and D202N mutations. The same immunostaining method using anti-betaA4 and anti-14.3.3 zeta antibodies revealed no colocalization in patients with AD. Our data suggest that 14.3.3 zeta protein could interact either with PrP or with other components of PrP(sc) deposits in CJD.