Presenting symptoms, clinical course and paraclinical findings in childhood Guillain-Barré syndrome (GBS) have rarely been investigated prospectively. We performed a multicentre study in GBS diagnosed according to international criteria. Clinical findings were recorded using an ordinal GBS score and additional scores for arm, cranial nerve and vegetative function, and pain. Electrophysiological and CSF investigations followed individual procedures in the local hospitals. Ninety-five children with a median age of 6.2 years were registered over 40 months (53 boys, 42 girls). 70 had suffered an infection and 8 had been vaccinated during the previous 6 weeks. The first symptom was usually a disturbance of gait or neuropathic pain. The symptoms progressed for a median of 7 days. At the height of the disease, 60% of patients were unable to walk and 24% could not use their arms. 46% showed cranial nerve involvement, and 51% autonomous dysfunction. 13% required artificial ventilation. 79% complained of neuropathic pain, half of them to a severe degree. Electrophysiological examination showed demyelination in 74%, and 26% of these presented with very low amplitude compound action potentials. Purely axonal changes were found in 11%. All but eight were treated with I.V. immunoglobulin. Improvement began on day 13 after the first symptom (median). Ability to walk unaided returned after 27 days. In the children observed over the long-term, it took 118 days for them to be free of symptoms. Transient deterioration after immunoglobulin treatment occurred in seven patients, two suffered relapsing GBS, and three developed CIDP. At the end of the observation period (288 days), 75% of patients were free of symptoms. 21% suffered residual symptoms having no effect on daily functioning. The more severely disabled 4% either suffered from CIDP or concurrent myelitis. With this prospective study, the results of earlier retrospective investigations are confirmed. Besides pareses and respiratory compromise, severe neuropathic pain frequently is a therapeutic challenge during the acute phase of the disease. The long-term prognosis is good for most children. However, a change to CIDP and concurrent myelitis can give rise to a worse prognosis.

Reducing body myopathy (RBM) is a rare disorder causing progressive muscular weakness characterized by aggresome-like inclusions in the myofibrils. Identification of genes responsible for RBM by traditional genetic approaches has been impossible due to the frequently sporadic occurrence in affected patients and small family sizes. As an alternative approach to gene identification, we used laser microdissection of intracytoplasmic inclusions identified in patient muscle biopsies, followed by nanoflow liquid chromatography-tandem mass spectrometry and proteomic analysis. The most prominent component of the inclusions was the Xq26.3-encoded four and a half LIM domain 1 (FHL1) protein, expressed predominantly in skeletal but also in cardiac muscle. Mutational analysis identified 4 FHL1 mutations in 2 sporadic unrelated females and in 2 families with severely affected boys and less-affected mothers. Transfection of kidney COS-7 and skeletal muscle C2C12 cells with mutant FHL1 induced the formation of aggresome-like inclusions that incorporated both mutant and wild-type FHL1 and trapped other proteins in a dominant-negative manner. Thus, a novel laser microdissection/proteomics approach has helped identify both inherited and de novo mutations in FHL1, thereby defining a new X-linked protein aggregation disorder of muscle.

Abbreviations used in this paper: CsA, cyclosporine A; CSA, cross-sectional area; EDL, extensor digitorum longus; FDP, fl exor digitorum profundus; FHL, fourand-a-half LIM protein; HSA, human skeletal muscle ␣ -actin; LIM, Lin-11, Isl-1, Mec-3; MHC, myosin heavy chain; NBT, nitro blue tetrazolium chloride; NFAT, nuclear factor of activated T cells; RBM, reducing body myopathy.

Treatment with IVIG before loss of unaided walking did not give rise to a less severe course, but recovery occurred somewhat faster. However, given the small number of patients, the power of this conclusion is low. For treatment after loss of unaided walking, there was no significant difference in the effectiveness of 2 g/kg IVIG administered over 2 days versus 5 days. Early "relapses" occurred more frequently after the shorter treatment regimen.

We recently identified the X-chromosomal four and a half LIM domain gene FHL1 as the causative gene for reducing body myopathy, a disorder characterized by progressive weakness and intracytoplasmic aggregates in muscle that exert reducing activity on menadione nitro-blue-tetrazolium (NBT). The mutations detected in FHL1 affected highly conserved zinc coordinating residues within the second LIM domain and lead to the formation of aggregates when transfected into cells. Our aim was to define the clinical and morphological phenotype of this myopathy and to assess the mutational spectrum of FHL1 mutations in reducing body myopathy in a larger cohort of patients. Patients were ascertained via the detection of reducing bodies in muscle biopsy sections stained with menadione-NBT followed by clinical, histological, ultrastructural and molecular genetic analysis. A total of 11 patients from nine families were included in this study, including seven sporadic patients with early childhood onset disease and four familial cases with later onset. Weakness in all patients was progressive, sometimes rapidly so. Respiratory failure was common and scoliosis and spinal rigidity were significant in some of the patients. Analysis of muscle biopsies confirmed the presence of aggregates of FHL1 positive material in all biopsies. In two patients in whom sequential biopsies were available the aggregate load in muscle sections appeared to increase over time. Ultrastructural analysis revealed that cytoplasmic bodies were regularly seen in conjunction with the reducing bodies. The mutations detected were exclusive to the second LIM domain of FHL1 and were found in both sporadic as well as familial cases of reducing body myopathy. Six of the nine mutations affected the crucial zinc coordinating residue histidine 123. All mutations in this residue were de novo and were associated with a severe clinical course, in particular in one male patient (H123Q). Mutations in the zinc coordinating residue cysteine 153 were associated with a milder phenotype and were seen in the familial cases in which the boys were still more severely affected compared to their mothers. We expect the mild end of the spectrum to significantly expand in the future. On the severe end of the spectrum we define reducing body myopathy as a progressive disease with early, but not necessarily congenital onset, distinguishing this condition from the classic essentially non-progressive congenital myopathies.

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IntroductionMyofibrillar myopathies are characterized by progressive muscle weakness and impressive abnormal protein aggregation in muscle fibers. In about 10 % of patients, the disease is caused by mutations in the MYOT gene encoding myotilin. The aim of our study was to decipher the composition of protein deposits in myotilinopathy to get new information about aggregate pathology.ResultsSkeletal muscle samples from 15 myotilinopathy patients were included in the study. Aggregate and control samples were collected from muscle sections by laser microdissection and subsequently analyzed by a highly sensitive proteomic approach that enables a relative protein quantification. In total 1002 different proteins were detected. Seventy-six proteins showed a significant over-representation in aggregate samples including 66 newly identified aggregate proteins. Z-disc-associated proteins were the most abundant aggregate components, followed by sarcolemmal and extracellular matrix proteins, proteins involved in protein quality control and degradation, and proteins with a function in actin dynamics or cytoskeletal transport. Forty over-represented proteins were evaluated by immunolocalization studies. These analyses validated our mass spectrometric data and revealed different regions of protein accumulation in abnormal muscle fibers. Comparison of data from our proteomic analysis in myotilinopathy with findings in other myofibrillar myopathy subtypes indicates a characteristic basic pattern of aggregate composition and resulted in identification of a highly sensitive and specific diagnostic marker for myotilinopathy.ConclusionsOur findings i) indicate that main protein components of aggregates belong to a network of interacting proteins, ii) provide new insights into the complex regulation of protein degradation in myotilinopathy that may be relevant for new treatment strategies, iii) imply a combination of a toxic gain-of-function leading to myotilin-positive protein aggregates and a loss-of-function caused by a shift in subcellular distribution with a deficiency of myotilin at Z-discs that impairs the integrity of myofibrils, and iv) demonstrate that proteomic analysis can be helpful in differential diagnosis of protein aggregate myopathies.Electronic supplementary materialThe online version of this article (doi:10.1186/s40478-016-0280-0) contains supplementary material, which is available to authorized users.

BackgroundDysferlinopathies are autosomal recessive disorders caused by mutations in the dysferlin (DYSF) gene encoding the dysferlin protein. DYSF mutations lead to a wide range of muscular phenotypes, with the most prominent being Miyoshi myopathy (MM) and limb girdle muscular dystrophy type 2B (LGMD2B).MethodsWe assessed the one-year-natural course of dysferlinopathy, and the safety and efficacy of deflazacort treatment in a double-blind, placebo-controlled cross-over trial. After one year of natural course without intervention, 25 patients with genetically defined dysferlinopathy were randomized to receive deflazacort and placebo for six months each (1 mg/kg/day in month one, 1 mg/kg every 2nd day during months two to six) in one of two treatment sequences.ResultsDuring one year of natural course, muscle strength declined about 2% as measured by CIDD (Clinical Investigation of Duchenne Dystrophy) score, and 76 Newton as measured by hand-held dynamometry. Deflazacort did not improve muscle strength. In contrast, there is a trend of worsening muscle strength under deflazacort treatment, which recovers after discontinuation of the study drug. During deflazacort treatment, patients showed a broad spectrum of steroid side effects.ConclusionDeflazacort is not an effective therapy for dysferlinopathies, and off-label use is not warranted. This is an important finding, since steroid treatment should not be administered in patients with dysferlinopathy, who may be often misdiagnosed as polymyositis.Trial registrationThis clinical trial was registered at http://www.ClincalTrials.gov, identifier: NCT00527228, and was always freely accessible to the public.