Late onset Pompe disease: clinical and neurophysiological spectrum of 38 patients including long-term follow-up in 18 patients.

To describe the clinical and neurophysiological spectrum and prognosis in a large cohort of biochemically and genetically proven late onset Pompe patients. Thirty-eight diagnosed with late onset Pompe disease at our neuromuscular department during 1985 and 2006 are described in detail. The mean delay from onset of symptoms or first medical consultation until diagnosis was 10.4 and 7.1 years, respectively. A different diagnosis was suggested in 11 of 38 patients. Ten patients underwent repeated muscle biopsies before diagnosis of Pompe disease was established. Limb girdle weakness was the most frequent presenting sign. Six patients complained of myalgia. Wolf-Parkinson-White syndrome was found in 3 of 38 patients. Respiratory failure preceded the onset of overt limb muscle weakness in three patients. The course of the patients was progressive in all, but there was a wide variety of progression, which did not correlate with the age of disease onset. In 71% of the patients, neurophysiological investigations revealed a myopathic EMG pattern, half of the patients had spontaneous activity including complex repetitive discharges. A normal EMG was found in 9% of the patients. Nerve conduction studies were normal in all. Pompe disease should be taken into consideration in patients with unexplained limb girdle muscular weakness with respiratory failure. Cardiac manifestations may not be restricted to infantile Pompe disease.

Therapeutic options in autoimmune inflammatory myopathies (dermatomyositis, polymyositis, inclusion body myositis).

Polymyositis, dermatomyositis, and inclusion body myositis are idiopathic inflammatory myopathies of unknown etiology with autoimmune pathogenesis. For choosing an individual and efficient therapy, diagnostic assignment is an important factor. Therapeutic options in dermatomyositis and polymyositis include corticosteroids and immunosuppressives. Intravenous immunoglobulins are only needed in special cases. In inclusion body myositis, corticosteroids and immunosuppressives are not successful. At the moment intravenous immunoglobulins are the only therapeutic possibility.

Extraocular mitochondrial myopathies and their differential diagnoses.

The diagnosis of mitochondrial myopathy depends upon a constellation of findings, family history, type of muscle involvement, specific laboratory abnormalities, and the results of histological, pathobiochemical and genetic analysis. In the present paper, the authors describe the diagnostic approach to mitochondrial myopathies manifesting as extraocular muscle disease. The most common ocular manifestation of mitochondrial myopathy is progressive external ophthalmoplegia (PEO). To exclude myasthenia gravis, ocular myositis, thyroid associated orbitopathy, oculopharyngeal muscular dystrophy, and congenital fibrosis of the extraocular muscles in patients with an early onset or long-lasting very slowly progressive ptosis and external ophthalmoplegia, almost without any diplopia, and normal to mildly elevated serum creatine kinase and lactate, electromyography, nerve conduction studies and MRI of the orbits should be performed. A PEO phenotype forces one to look comprehensively for other multisystemic mitochondrial features (e.g., exercise induced weakness, encephalopathy, polyneuropathy, diabetes, heart disease). Thereafter, and presently even in familiar PEO, a diagnostic muscle biopsy should be taken. Histological and ultrastructural hallmarks are mitochondrial proliferations and structural abnormalities, lipid storage, ragged-red fibers, or cytochrome-C negative myofibers. In addition, Southern blotting may reveal the common deletion, or molecular analysis may verify specific mutations of distinct mitochondrial or nuclear genes.

Novel splice site mutation in the caveolin-3 gene leading to autosomal recessive limb girdle muscular dystrophy.

Mutations in CAV3 gene encoding the protein caveolin-3 are associated with autosomal dominant limb girdle muscular dystrophy 1C, rippling muscle disease, hyperCKemia, distal myopathy, hypertrophic cardiomyopathy and rare autosomal recessive limb girdle muscular dystrophy phenotypes. In a 57-year-old patient with asymmetric limb girdle weakness, we detected a novel homozygous intronic mutation (IVS1 + 2T > C) of the CAV3 gene. This is the first splicing mutation reported for CAV3. These findings add to the clinical and genetic variability of CAV3 mutations.

Deletion of the LMNA initiator codon leading to a neurogenic variant of autosomal dominant Emery-Dreifuss muscular dystrophy.

Mutations in the LMNA gene encoding the nuclear envelope protein, lamins A and C, have been associated with at least nine distinct disorders now called laminopathies, including Emery-Dreifuss muscular dystrophy and Charcot-Marie-Tooth type 2 disease. We identified a novel mutation in the 5' region of the LMNA gene -3del15, resulting in the loss of 15 nucleotides from -3 to +12, including the translation ATG initiator codon. The mutation segregates in a previously described family with a clinical phenotype that shared features of both Emery-Dreifuss muscular dystrophy and Charcot-Marie-Tooth type 2. Thus, the mutation with this unique phenotypical expression represents the first example for a link between the neurogenic and myogenic phenotypes and extends the clinical variability of laminopathies.

Pattern of interleukin-6 receptor complex immunoreactivity between cortical regions of rapid autopsy normal and Alzheimer's disease brain.

Involvement of the interleukin-6 receptor complex (IL-6RC) in neuroregulatory and immunological processes of the brain and particularly in Alzheimer's disease (AD) has been hypothesized. The functionally active IL-6RC consists of the cytokine IL-6, which acts through the ligand binding IL-6R and the signal transducing gp130. Using a new immunocytochemical protocol on rapid autopsy cryostat brain sections we studied the expression of the IL-6RC in Braak IV-V staged AD patients compared to normal age-matched controls (HC) across five different cortical regions. Inter-rater reliability of the method was high. The "baseline" expression in normal human brain was determined for IL-6,IL-6R and gp130 in all cortical regions. In normal tissue IL-6 expression was lower in parietal cortex. Higher IL-6R expression was shown in frontal, occipital and parietal cortex, lower expression in temporal cortex and cerebellum. In AD IL-6 expression levels were generally increased in parietal cortex and decreased in occipital cortex compared to controls. IL-6R expression levels were strongly increased in AD frontal and occipital cortex and decreased in temporal cortex and cerebellum. Our findings indicate an altered cortical immunoreactivity pattern of the functional IL-6RC in AD supporting the hypothesis of a disease-related role of IL-6 in AD pathophysiology.

Mutational analysis of serotonin receptor genes: HTR3A and HTR3B in fibromyalgia patients.

The neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) has been implicated in numerous human disorders. Dysfunction of serotonergic neurotransmission is thought to play a major role in the pathophysiology of the fibromyalgia syndrome (FMS) which is characterised by non-restorative sleep and severe pain. In our study, both serotonin receptor subunit genes, HTR3A and HTR3B, have been investigated for sequence variations in FMS patients in order to reveal a possible involvement in the aetiology of FMS. We examined DNA samples from 48 patients with FMS representing sporadic cases by single-strand conformation polymorphism (SSCP) and denaturing high-performance liquid chromatography (dHPLC) analysis, sequenced samples with conspicuous patterns and performed statistical calculations. HTR3A mutational analysis revealed one novel as well as five known sequence variations. Investigating HTR3B, we detected seven formerly described mutations and one novel sequence variant. Statistical computation rated all variants as probably non-disease-related polymorphisms. Nevertheless, one might speculate about an effect of the respective sequence variants on the severity of the disease. Sequence variants of the serotonin receptor subunit genes HTR3A and HTR3B indicate no obvious significance in the aetiology of fibromyalgia, yet they represent the basis for future studies on their pharmacogenetic relevance.

The long-term outcome of anti-Jo-1-positive inflammatory myopathies.

OBJECTIVE: To determine the response to treatment and the long-term outcome of patients with the antisynthetase syndrome associated with anti-Jo-1-antibodies. PATIENTS AND METHODS: A total of 12 patients with histologically proven myositis and anti-Jo-1-autoantibodies were evaluated over a mean follow-up period of 66.4 months. In all patients neuromuscular function tests, electromyographic examinations, pulmonary function tests and high-resolution-computed tomography of the lungs were performed regularly. RESULTS: Muscle function improved in all patients with treatment, and a complete clinical response was achieved in 5 patients. Pulmonary function worsened in 1 patient, who died from respiratory failure, but normalised in 4 patients. Arthropathy progressed despite improvement of myositis and pulmonary status in 2 patients. Discontinuation of treatment was facilitated in 1 patient, although long-term therapy was required in 10 patients. In 2 patients with refractory disease, treatment with intravenous immunoglobulins was successful. Severe side effects of treatment occurred in 7 patients and overall mortality rate was one of 12 (8 %). CONCLUSION: The antisynthetase syndrome associated with anti-Jo-1-antibodies requires long-term immunosuppressive therapy in most patients. Whereas a complete clinical response of muscular symptoms is frequent, continued deterioration of the pulmonary system may occur despite immunosuppressive treatment, and may lead to fatal outcome. An interdisciplinary therapeutic approach is necessary for best possible results in these patients.

Muscle pathology in 57 patients with myotonic dystrophy type 2.

We evaluated muscle biopsies from 57 patients with genetically confirmed myotonic dystrophy type 2/proximal myotonic myopathy (DM2/PROMM). Light microscopy showed myopathic together with "denervation-like" changes in almost all biopsies obtained from four different muscles: increased fiber size variation, internal nuclei, small angulated fibers, pyknotic nuclear clumps, and predominant type 2 fiber atrophy. Quantitative morphometry in 18 biopsies that were immunostained for myosin heavy chain confirmed a predominance of nonselective type 2 fiber atrophy. These histological changes were similar in all patients regardless of the site of biopsy, the predominant clinical symptoms and signs, and the clinical course. It is likely that, in a number of undiagnosed patients, DM2 is the underlying disorder. With a better understanding of the histopathological pattern in DM2, biopsies from patients with undiagnosed neuromuscular disorders can now be reevaluated.

Variable reduction of caveolin-3 in patients with LGMD2B/MM.

Mutations in the human dysferlin gene ( DYSF) cause autosomal recessive muscular dystrophies characterized by degeneration and weakness of proximal and/or distal muscles: limb girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi myopathy (MM). Recently, an interaction between caveolin-3 and dysferlin in normal and dystrophic muscle (primary caveolin-3 deficiency; LGMD1C) was shown. In this study, clinical,morphological and genetic analysis was carried out in four independent LGMD2B/MM patients. All patients presented with an adult-onset, slowly progressive muscular dystrophy with variable involvement of proximal and distal muscles. We found complete lack of dysferlin in the four LGMD2B/MM patients. Secondary reduction of caveolin-3 was detected in three out of the four patients. Regular caveolae were detected along the basal lamina in two patients by electron microscopy. We provide further evidence that dysferlin and caveolin-3 interact in human skeletal muscle. It remains to be elucidated whether the loss of this interaction contributes to pathogenic events in muscular dystrophy.

A novel homozygous missense mutation in the GNE gene of a patient with quadriceps-sparing hereditary inclusion body myopathy associated with muscle inflammation.

An adult-onset hereditary inclusion body myopathy with sparing of the quadriceps muscle was originally described in Iranian Jews and assigned to a locus on chromosome 9p12-p13. Recently, mutations of the UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase (GNE) gene were reported to cause hereditary inclusion body myopathy and one type of distal myopathy in a world-wide distribution. Importantly, the lack of muscle inflammation was used to distinguish hereditary inclusion body myopathy from the sporadic form of inclusion body myopathy. We report a case of a quadriceps-sparing myopathy in a non-Jewish, Iranian patient with a high degree of muscle inflammation. A novel homozygous G-to-A mutation (128933G-->A) in exon 7 changing a valine to isoleucine (V367I) in the epimerase domain of the GNE gene was found. We conclude that muscle inflammation is not sufficient to exclude the diagnosis of hereditary inclusion body myopathy.

Muscle glycogenosis with low phosphorylase kinase activity: mutations in PHKA1, PHKG1 or six other candidate genes explain only a minority of cases.

Muscle-specific deficiency of phosphorylase kinase (Phk) causes glycogen storage disease, clinically manifesting in exercise intolerance with early fatiguability, pain, cramps and occasionally myoglobinuria. In two patients and in a mouse mutant with muscle Phk deficiency, mutations were previously found in the muscle isoform of the Phk alpha subunit, encoded by the X-chromosomal PHKA1 gene (MIM # 311870). No mutations have been identified in the muscle isoform of the Phk gamma subunit (PHKG1). In the present study, we determined Q1the structure of the PHKG1 gene and characterized its relationship to several pseudogenes. In six patients with adult- or juvenile-onset muscle glycogenosis and low Phk activity, we then searched for mutations in eight candidate genes. The coding sequences of all six genes that contribute to Phk in muscle were analysed: PHKA1, PHKB, PHKG1, CALM1, CALM2 and CALM3. We also analysed the genes of the muscle isoform of glycogen phosphorylase (PYGM), of a muscle-specific regulatory subunit of the AMP-dependent protein kinase (PRKAG3), and the promoter regions of PHKA1, PHKB and PHKG1. Only in one male patient did we find a PHKA1 missense mutation (D299V) that explains the enzyme deficiency. Two patients were heterozygous for single amino-acid replacements in PHKB that are of unclear significance (Q657K and Y770C). No sequence abnormalities were found in the other three patients. If these results can be generalized, only a fraction of cases with muscle glycogenosis and a biochemical diagnosis of low Phk activity are caused by coding, splice-site or promoter mutations in PHKA1, PHKG1 or other Phk subunit genes. Most patients with this diagnosis probably are affected either by elusive mutations of Phk subunit genes or by defects in other, unidentified genes.

Depletion of mitochondrial DNA in the liver of an infant with neonatal giant cell hepatitis.

A boy presented with lactic acidosis, hepatomegaly, hypoglycemia, generalised icterus, and muscle hypotonia in the first weeks of life. At the age of 2 months, neonatal giant cell hepatitis was diagnosed by light microscopy. Electron microscopy of the liver revealed an accumulation of abnormal mitochondria and steatosis. Skeletal muscle was normal on both light and electron microscopy. At the age of 5 months, the patient died of liver failure. Biochemical studies of the respiratory chain enzymes in muscle showed that cytochrome-c oxidase (complex IV) and succinate-cytochrome-c oxidoreductase (complex II + III) activities were (just) below the control range. When related to citrate synthase activity, however, complex IV and complex II + III activities were normal. Complex I activity was within the control range. The content of mitochondrial DNA (mtDNA) was severely reduced in the liver (17% to 18% of control values). Ultracytochemistry and immunocytochemistry of cytochrome-c oxidase demonstrated a mosaic pattern of normal and defective liver cells. In defective cells, a reduced amount of the mtDNA-encoded subunits II-III and the nuclear DNA-encoded subunits Vab was found. Cells of the biliary system were spared. Immunohistochemistry of mtDNA replication factors revealed normal expression of DNA polymerase gamma. The mitochondrial single-stranded binding protein (mtSSB) was absent in some abnormal hepatocytes, whereas the mitochondrial transcription factor A (mtTFA) was deficient in all abnormal hepatocytes. In conclusion, depletion of mtDNA may present as giant cell hepatitis. mtTFA and to a lesser degree mtSSB are reduced in mtDNA depletion of the liver and may, therefore, be of pathogenetic importance. The primary defect, however, is still unknown.

A newly identified chromosomal microdeletion and an N-box mutation of the AChR epsilon gene cause a congenital myasthenic syndrome.

Congenital myasthenic syndromes (CMSs) are frequently caused by mutations of the coding region of the acetylcholine receptor epsilon subunit (AChRepsilon) gene leading to a reduced expression of the acetylcholine receptor (AChR) at the postsynaptic membrane. Two recent observations have linked two different N-box mutations of the human AChRepsilon promoter to a clinical CMS phenotype. N-boxes are regulatory sequence elements of mammalian promoters that confer synapse-specific expression of several genes, including the AChR subunit genes. Here, we report on a novel point mutation (epsilon-154G-->A) in the N-box of the AChRepsilon promoter in a German CMS pedigree. Semiquantitative analysis of AChRepsilon mRNA levels in the patient's muscle indicated significantly impaired AChRepsilon expression. We provide additional evidence of a pathogenic role for this mutation using the mutated promoter (epsilon-154G-->A) driving a heterologous gene (luciferase) in rat skeletal muscle. We show that agrin-induced gene expression is significantly reduced by the N-box mutant (mt) compared with the wild-type (wt) promoter. Refined haplotype analysis and direct sequencing revealed maternal inheritance of the mutant AChRepsilon promoter (epsilon-154G-->A) together with paternal inheritance of a chromosomal microdeletion (Delta1290 bp) encompassing the promoter and the first two exons of the AChRepsilon gene in the index patient. In conclusion, we provide genetic and functional evidence that a mutation of the AChRepsilon subunit promoter (epsilon-154G-->A) causes CMS due to the reduction of gene expression in skeletal muscle. Moreover, this is the first report of a chromosomal microdeletion affecting an AChR gene. This type of mutation may be missed in standard screening techniques of CMS patients.

Creatine monohydrate in myotonic dystrophy: a double-blind, placebo-controlled clinical study.

We assessed safety and efficacy of creatine monohydrate (Cr) in myotonic dystrophy (DM1) in a double-blind, cross-over trial. Thirty-four patients with defined DM1 were randomized to receive Cr and placebo for eight weeks (10.6 g day 1-10, 5.3 g day 11-56) in one of 2 treatment sequences. There was no significant improvement using manual and quantitative muscle strength, daily-life activities, and patients' own global assessment comparing verum with placebo administration. Cr supplementation was well tolerated without clinically relevant side effects, but did not result in significant improvement of muscle strength or daily-life activities.