Novel SBF2 mutations and clinical spectrum of Charcot-Marie-Tooth neuropathy type 4B2.

Biallelic SBF2 mutations cause Charcot-Marie-Tooth disease type 4B2 (CMT4B2), a sensorimotor neuropathy with autosomal recessive inheritance and association with glaucoma. Since the discovery of the gene mutation, only few additional patients have been reported. We identified seven CMT4B2 families with nine different SBF2 mutations. Revisiting genetic and clinical data from our cohort and the literature, SBF2 variants were private mutations, including exon-deletion and de novo variants. The neuropathy typically started in the first decade after normal early motor development, was predominantly motor and had a rather moderate course. Electrophysiology and nerve biopsies indicated demyelination and excess myelin outfoldings constituted a characteristic feature. While neuropathy was >90% penetrant at age 10 years, glaucoma was absent in ~40% of cases but sometimes developed with age. Consequently, SBF2 mutation analysis should not be restricted to individuals with coincident neuropathy and glaucoma, and CMT4B2 patients without glaucoma should be followed for increased intraocular pressure. The presence of exon-deletion and de novo mutations demands comprehensive mutation scanning and family studies to ensure appropriate diagnostic approaches and genetic counseling.

[Multiple sclerosis in childhood and adolescence : Complex, chronic and differentiated]. / Multiple Sklerose im Kindes- und Jugendalter : Komplex, chronisch, differenziert.

Pediatric multiple sclerosis (MS) is one of the most important acquired neurological disorders in childhood and adolescence. A timely recognition, diagnosis and treatment are of utmost importance. This article highlights the current state of knowledge on the etiology, pathogenesis, diagnosis, clinical presentation and treatment in childhood. Although the rate of progression of disability in the early years is slower in younger patients compared to adults, a disease-modifying therapy should be started once MS is diagnosed.

[Spinal muscular atrophy : Time for newborn screening?] / Spinale Muskelatrophie : Zeit für das Neugeborenenscreening?

The most common neurodegenerative disease in childhood is spinal muscular atrophy (SMA). The severe infantile type 1 (Werdnig-Hoffman disease) makes 60% of SMA in total. These children usually die within 18 months without ventilation. New therapeutic approaches have led from the theoretical concept to randomized controlled clinical trials in patients. For the first time, a pharmacological treatment of SMA has been approved. The early detection of the disease is decisive for the success of therapy. All previous data suggest starting treatment early and when possible prior to the onset of symptoms considerably improves the outcome in comparison to a delayed start. The goal must be the presymptomatic diagnosis in order to initiate treatment before motor neuron degeneration. Technical and ethical prerequisites for a molecular genetic newborn screening are given.

Diagnostic algorithms in Charcot-Marie-Tooth neuropathies: experiences from a German genetic laboratory on the basis of 1206 index patients.

We present clinical features and genetic results of 1206 index patients and 124 affected relatives who were referred for genetic testing of Charcot-Marie-Tooth (CMT) neuropathy at the laboratory in Aachen between 2001 and 2012. Genetic detection rates were 56% in demyelinating CMT (71% of autosomal dominant (AD) CMT1/CMTX), and 17% in axonal CMT (24% of AD CMT2/CMTX). Three genetic defects (PMP22 duplication/deletion, GJB1/Cx32 or MPZ/P0 mutation) were responsible for 89.3% of demyelinating CMT index patients in whom a genetic diagnosis was achieved, and the diagnostic yield of the three main genetic defects in axonal CMT (GJB1/Cx32, MFN2, MPZ/P0 mutations) was 84.2%. De novo mutations were detected in 1.3% of PMP22 duplication, 25% of MPZ/P0, and none in GJB1/Cx32. Motor nerve conduction velocity was uniformly <38 m/s in median or ulnar nerves in PMP22 duplication, >40 m/s in MFN2, and more variable in GJB1/Cx32, MPZ/P0 mutations. Patients with CMT2A showed a broad clinical severity regardless of the type or position of the MFN2 mutation. Out of 75 patients, 8 patients (11%) with PMP22 deletions were categorized as CMT1 or CMT2. Diagnostic algorithms are still useful for cost-efficient mutation detection and for the interpretation of large-scale genetic data made available by next generation sequencing strategies.

Mitochondrial DNA depletion and fatal infantile hepatic failure due to mutations in the mitochondrial polymerase γ (POLG) gene: a combined morphological/enzyme histochemical and immunocytochemical/biochemical and molecular genetic study.

Combined morphological, immunocytochemical, biochemical and molecular genetic studies were performed on skeletal muscle, heart muscle and liver tissue of a 16-months boy with fatal liver failure. The pathological characterization of the tissues revealed a severe depletion of mtDNA (mitochondrial DNA) that was most pronounced in liver, followed by a less severe, but still significant depletion in skeletal muscle and the heart. The primary cause of the disease was linked to compound heterozygous mutations in the polymerase γ (POLG) gene (DNA polymerase γ; A467T, K1191N). We present evidence, that compound heterozygous POLG mutations lead to tissue selective impairment of mtDNA replication and thus to a mosaic defect pattern even in the severely affected liver. A variable defect pattern was found in liver, muscle and heart tissue as revealed by biochemical, cytochemical, immunocytochemical and in situ hybridization analysis. Functionally, a severe deficiency of cytochrome-c-oxidase (cox) activity was seen in the liver. Although mtDNA depletion was detected in heart and skeletal muscle, there was no cox deficiency in these tissues. Depletion of mtDNA and microdissection of cox-positive or negative areas correlated with the histological pattern in the liver. Interestingly, the mosaic pattern detected for cox-activity and mtDNA copy number fully aligned with the immunohistologically revealed defect pattern using Pol γ, mtSSB- and mtTFA-antibodies, thus substantiating the hypothesis that nuclear encoded proteins located within mitochondria become unstable and are degraded when they are not actively bound to mtDNA. Their disappearance could also aggravate the mtDNA depletion and contribute to the non-homogenous defect pattern.

Rare intronic mutation between Exon 62 and 63 (c.9225-285A>G) of the dystrophin gene associated with atypical BMD phenotype.

Dystrophinopathies are predominantly caused by deletions, duplications and point mutations in the coding regions of the dystrophin gene with less than 1% of all pathogenic mutations identified within intronic sequences. We describe a 17-year-old male with a Becker muscular dystrophy diagnosis and mental disability due to an intron mutation that led to aberrant splicing and formation of an additional exon. Histopathological analysis of muscle tissue revealed signs of muscular dystrophy and reduced signal for dystrophin, alpha-sarcoglycan, and alpha-dystroglycan. Multiplex ligation-dependent probe amplification screening and total sequencing of the dystrophin gene did not identify a mutation in the coding regions. However, next generation sequencing revealed an intron mutation between exons 62 and 63 of the dystrophin gene known for pseudoexon formation and disruption of the reading frame. We report a functional consequence of this mutation as an increased intracellular-weighted sodium signal (assessed by 23Na-magnetic resonance imaging) in leg muscles.

Qualitative and quantitative muscle ultrasound in patients with Duchenne muscular dystrophy: Where do sonographic changes begin?

OBJECTIVE: The number of studies investigating and understanding the disease mechanisms of Duchenne muscular dystrophy (DMD) in human clinical trials have increased substantially over the last decade. Suitable clinical instruments for the measurement of disease progress and drug efficiency are mandatory, but currently not available, especially in the youngest patients. The aim of this study was to detect a reproducible pattern of muscle involvement in early stages potentially preceding evidence of motor regression. MATERIAL AND METHODS: A cohort of 25 DMD patients aged 1-6 years at the first presentation were examined at multiple timepoints and compared with age-matched healthy controls. Muscle ultrasound was quantified using computer-analyzed gray scale levels (GSL) and blinded visual rating, using a modified Heckmatt scale. RESULTS: Changes in muscle echogenicity in DMD patients occurred very early, clearly preceding motor regression and in some cases, even before the motor plateau phase was reached. Visual rating and GSL identified the earliest changes in the proximal adductor magnus muscle. CONCLUSION: Muscle ultrasound can be used as an additional method to assess the disease progression and for decision-making in paucisymptomatic DMD patients. Sonographic changes in the ad-ductor magnus muscle seem to be the first detectable changes with a recognisable pattern.

Diagnosis and treatment of Guillain-Barré Syndrome in childhood and adolescence: An evidence- and consensus-based guideline.

This evidence- and consensus-based practical guideline for the diagnosis and treatment of Guillain-Barré Syndrome (GBS) in childhood and adolescence has been developed by a group of delegates from relevant specialist societies and organisations; it is the result of an initiative by the German-Speaking Society of Neuropediatrics (GNP), and is supported by the Association of Scientific Medical Societies (AWMF, Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften). A systematic analysis of the literature revealed that only a few adequately-controlled studies exist for this particular age group, while none carries a low risk of bias. For this reason, the diagnostic and therapeutic recommendations largely rely on findings in adult patients with GBS, for which there are a higher number of suitable studies available. Consensus was established using a written, multi-step Delphi process. A high level of consensus could be reached for the crucial steps in diagnosis and treatment. We recommend basing the diagnostic approach on the clinical criteria of GBS and deriving support from CSF and electrophysiological findings. Repetition of invasive procedures that yield ambiguous results is only recommended if the diagnosis cannot be ascertained from the other criteria. For severe or persistently-progressive GBS treatment with intravenous immunoglobulin (IVIG) is recommended, whereas in cases of IVIG intolerance or inefficacy we recommended treatment with plasmapheresis. Corticosteroids are ineffective for GBS but can be considered when acute onset chronic inflammatory demyelinating polyneuropathy (A-CIDP) is suspected due to a prolonged disease course. The full German version of the Guideline is available on the AWMF website (https://www.awmf.org/leitlinien/detail/ll/022-008.html).

Methods for a prompt and reliable laboratory diagnosis of Pompe disease: report from an international consensus meeting.

Pompe disease is an autosomal recessive disorder of glycogen metabolism caused by a deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA). It presents at any age, with variable rates of progression ranging from a rapidly progressive course, often fatal by one-year of age, to a more slowly, but nevertheless relentlessly progressive course, resulting in significant morbidity and premature mortality. In infants, early initiation of enzyme replacement therapy is needed to gain the maximum therapeutic benefit, underscoring the need for early diagnosis. Several new methods for measuring GAA activity have been developed. The Pompe Disease Diagnostic Working Group met to review data generated using the new methods, and to establish a consensus regarding the application of the methods for the laboratory diagnosis of Pompe disease. Skin fibroblasts and muscle biopsy have traditionally been the samples of choice for measuring GAA activity. However, new methods using blood samples are rapidly becoming adopted because of their speed and convenience. Measuring GAA activity in blood samples should be performed under acidic conditions (pH 3.8-4.0), using up to 2 mM of the synthetic substrate 4-methylumbelliferyl-alpha-D-glucoside or glycogen (50 mg/mL), in the presence of acarbose (3-9 microM) to inhibit the isoenzyme maltase-glucoamylase. The activity of a reference enzyme should also be measured to confirm the quality of the sample. A second test should be done to support the diagnosis of Pompe disease until a program for external quality assurance and proficiency testing of the enzymatic diagnosis in blood is established.

Early-Onset Myopathies: Clinical Findings, Prevalence of Subgroups and Diagnostic Approach in a Single Neuromuscular Referral Center in Germany.

BACKGROUND: Early-onset myopathies are a heterogeneous group of neuromuscular diseases with broad clinical, genetic and histopathological overlap. The diagnostic approach has considerably changed since high throughput genetic methods (next generation sequencing, NGS) became available. OBJECTIVE: We present diagnostic subgroups in a single neuromuscular referral center and describe an algorithm for the diagnostic work-up. METHODS: The diagnostic approach of 98 index patients was retrospectively analysed. In 56 cases targeted sequencing of a known gene was performed, in 44 patients NGS was performed using large muscle specific panels, and in 12 individuals whole exome sequencing (WES) was undertaken. One patient was diagnosed via array CGH. Clinical features of all patients are provided. RESULTS: The final diagnosis could be found in 63 out of 98 patients (64%) with molecular genetic analysis. In 55% targeted gene sequencing could establish the genetic diagnosis. However, this rate largely depended on the presence of distinct histological or clinical features. NGS (large myopathy-related panels and WES) revealed genetic diagnosis in 58.5% (52% and 67%, respectively). The genes detected by WES in our cohort of patients were all covered by the panels. Based on our findings we propose an algorithm for a practical diagnostic approach.Prevalences:MTM1- and LAMA2-patients are the two biggest subgroups, followed by SEPN1-, RYR1- and Collagen VI-related diseases. 31% of genetically confirmed cases represents a group with overlap between "congenital myopathies (CM)" and "congenital muscular dystrophies (CMD)". In 36% of the patients a specific genetic diagnosis could not be assigned. CONCLUSIONS: A final diagnosis can be confirmed by high throughput genetic analysis in 58.5% of the cases, which is a higher rate than reported in the literature for muscle biopsy and should in many cases be considered as a first diagnostic tool. NGS cannot replace neuromuscular expertise and a close discussion with the geneticists on NGS is mandatory. Targeted candidate gene sequencing still plays a role in selected cases with highly suspicious clinical or histological features. There is a relevant clinical and genetic overlap between the entities CM and CMD.

Proximal muscular atrophy and weakness: An unusual adverse effect of deferasirox iron chelation therapy.

Deferasirox is a standard treatment for chronic transfusional iron overload. Adverse effects of deferasirox have been reported in large prospective studies. We report two cases of monozygotic twins manifesting with proximal muscular atrophy and weakness under deferasirox. Discontinuation of deferasirox resulted in symptom improvement and ultimately in complete remission five months after successful haematopoietic stem cell transplantation. Broad diagnostic work-up could not bring evidence of another aetiology of muscular weakness. Iron overload or beta thalassemia itself as a cause is considered unlikely in our patients because the chronological coincidence of muscular symptoms was contra-directional to serum ferritin levels and significant clinical improvement was observed promptly after cessation of deferasirox even before transplantation. These observations suggest that the development of muscular weakness in patients on deferasirox should be recognised as a possible adverse effect of the drug.

Diabetic neuropathy 3 years after successful pancreas and kidney transplantation.

Twenty-seven patients with successful transplantation and a control group of 14 patients with early rejection of the pancreas graft but functioning kidney graft were examined in a prospective study for 3 yr. Before transplantation, all patients had long-standing type I diabetes with advanced secondary complications, including end-stage diabetic nephropathy. After transplantation in the patients of both groups, kidney function was almost normal. Mean HbA1 levels were normal in the group with pancreas graft survival. In the control group, HbA1 levels were, on average, 1.5% higher compared with the group with pancreas survival (P = 0.00005). After 3 yr, the patients with functioning pancreas graft showed fewer symptoms (mean difference 1.0 in a symptom score ranging from 0 to 16, P = 0.004) compared with the control group. No statistically significant difference between both groups concerning clinical signs of polyneuropathy could be observed. In the pancreas and kidney transplantation group, peroneal and median nerve conduction velocities increased 7.2 m/s (P < 0.01) and 3.5 m/s (P < 0.05), respectively, whereas no increase was registered in the control group. The change of median and sural sensory nerve conduction velocities, peroneal and median compound muscle action potentials, and sural and median sensory action potentials was insignificant. In conclusion, although the improvement of clinical symptoms and neurophysiological signs of polyneuropathy was modest in the pancreas and kidney transplantation group, our data suggest that successful pancreas transplantation is able not only to halt the progression of diabetic polyneuropathy but also to improve it to some extent even at a far advanced stage.

Muscle ultrasound in classic infantile and adult Pompe disease: a useful screening tool in adults but not in infants.

A cohort of 4 infantile and 15 adult Pompe patients has been investigated regarding correlation between strength and ultrasound of skeletal musculature. In adults, muscle ultrasound is useful to assess clinical and subclinical involvement of muscles. In this study, visible sonographic changes were found in every clinically affected muscle, using a modified Heckmatt scale. In some muscles morphologic changes preceded weakness. Regarding the anatomical pattern of involvement, our findings do not support the hypothesis of a specific pattern with a higher vulnerability of vastus intermedius than rectus femoris, which has been postulated before. A frequent sparing of triceps brachii could be confirmed. Intramuscular abnormalities occurred in a focal, a diffuse, or an intermediate pattern, with characteristics of both. In contrast to muscular dystrophies, bone echogencity was not markedly decreased in Pompe disease even in an advanced stage. In infants, muscle ultrasound showed no distinct pathology even in clinically severely affected children and should not be used as a screening method for infantile Pompe disease.

A placebo-controlled crossover trial of creatine in mitochondrial diseases.

To test the efficacy and safety of creatine (Cr) monohydrate in mitochondrial diseases, 16 patients with chronic progressive external ophthalmoplegia or mitochondrial myopathy were randomized in a crossover design to receive double-blind placebo or 20 g Cr/day for 4 weeks. Cr was well tolerated, but there were no significant effects with regard to exercise performance, eye movements, or activities of daily life. The power of this pilot study was limited and future multicenter trials are needed.

Creatine monohydrate in muscular dystrophies: A double-blind, placebo-controlled clinical study.

The authors assessed the safety and efficacy of creatine monohydrate (Cr) in various types of muscular dystrophies in a double-blind, crossover trial. Thirty-six patients (12 patients with facioscapulohumeral dystrophy, 10 patients with Becker dystrophy, 8 patients with Duchenne dystrophy, and 6 patients with sarcoglycan-deficient limb girdle muscular dystrophy) were randomized to receive Cr or placebo for 8 weeks. There was mild but significant improvement in muscle strength and daily-life activities by Medical Research Council scales and the Neuromuscular Symptom Score. Cr was well tolerated throughout the study period.

Genetic identity of Marinesco-Sjögren/myoglobinuria and CCFDN syndromes.

OBJECTIVE AND BACKGROUND: To describe three Gypsy families with Marinesco-Sjögren syndrome (MSS), demyelinating neuropathy, and recurrent episodes of myoglobinuria in five of the six affected subjects. Because these families originated from the same genetically isolated founder population as did patients with congenital cataracts facial dysmorphism neuropathy (CCFDN) syndrome, and because the two syndromes have clinical manifestations in common, we hypothesized that the two related, albeit distinct, syndromes may represent clinical variants of a single genetic disorder. METHODS: Clinical studies were conducted and linkage and haplotype analyses were performed for the three families. A total of 16 individuals, including the 6 with MSS and 10 unaffected relatives, were genotyped for six polymorphic microsatellite markers from the CCFDN region on 18qter. RESULTS: Linkage analysis of markers in the 18qter region, where we previously had located the CCFDN gene, produced a lod score of 3.55, demonstrating colocalization of the gene responsible for MSS with demyelinating neuropathy and myoglobinuria with the CCFDN gene. Moreover, the patients with MSS shared the conserved marker haplotype found in CCFDN chromosomes. CONCLUSIONS: These data suggest that Marinesco-Sjögren syndrome with peripheral neuropathy and myoglobinuria, and congenital cataracts facial dysmorphism neuropathy syndrome are genetically identical and are caused by a single founder mutation.

A common mutation (epsilon1267delG) in congenital myasthenic patients of Gypsy ethnic origin.

OBJECTIVE: Mutation analysis of the acetylcholine receptor (AChR) epsilon subunit gene in patients with sporadic or autosomal recessive congenital myasthenic syndromes (CMS). BACKGROUND: The nicotinic AChR of skeletal muscle is a neurotransmitter-gated ion channel that mediates synaptic transmission at the vertebrate neuromuscular junction. Mutations in its gene may cause congenital myasthenic syndromes. A recently described mutation in exon 12 of the AChR epsilon subunit (epsilon1267delG) disrupts the cytoplasmic loop and the fourth transmembrane region (M4) of the AChR epsilon subunit. METHODS: Forty-three CMS patients from 35 nonrelated families were clinically classified as sporadic cases of CMS (group III according to European Neuromuscular Centre consensus) and were analyzed for epsilon1267delG by PCR amplification and sequence analysis. RESULTS: The authors report the complete genomic sequence and organization of the gene coding for the epsilon subunit of the human AChR (accession number AF105999). Homozygous epsilon1267delG was identified in 13 CMS patients from 11 independent families. All epsilon1267delG families were of Gypsy or southeastern European origin. Genotype analysis indicated that they derive from a common ancestor (founder) causing CMS in the southeastern European Gypsy population. Phenotype analysis revealed a uniform pattern of clinical features including bilateral ptosis and mild to moderate fatigable weakness of ocular, facial, bulbar, and limb muscles. CONCLUSIONS: The mutation epsilon1267delG might be frequent in European congenital myasthenic syndrome patients of Gypsy ethnic origin. In general, patients (epsilon1267delG) were characterized by the onset of symptoms in early infancy, the presence of ophthalmoparesis, positive response to anticholinesterase treatment, and the benign natural course of the disease.

Chronic myopathy in a patient suspected of carrying two malignant hyperthermia susceptibility (MHS) mutations.

Malignant hyperthermia (MH) is a pharmacogenetic myopathy triggered by a variety of anaesthetic agents and muscle relaxants. In humans, susceptibility to MH is inherited as an autosomal dominant trait, and susceptible patients do not show a clinically relevant myopathy unless having suffered from a MH crisis. Homozygosity for the MHS trait is thought to be an uncommon finding, and so far only a few cases of patients suggested to be homozygous for MH on the basis of pedigree information were reported and described as having a more severe form of this condition resulting in clinical symptoms also in the absence of triggering agents. We report clinical findings in a patient with chronic myopathy beginning at the age of 2 yr and associated with a number of unique features, the most important being a family history of MHS present in both parents. She became symptomatic with marked muscular weakness and elevated serum CK levels. A muscle biopsy showed a distinct enlargement and increase of muscle mitochondria. In the in vitro contracture test the patient's muscle responded with unusually high contractures already at basal levels of triggering agents indicating a particularly severe MHS condition. DNA markers for the MHS1 locus, described previously on chromosome 19q12-13.2 in Irish and Canadian pedigrees, could not be used to confirm her homozygous state because our molecular genetic studies had previously excluded the MHS trait in this pedigree from this locus.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunosuppressive treatment of rippling muscles in patients with myasthenia gravis.

Rippling muscle disease is a rare autosomal dominant disorder that may occur sporadically. In this report two patients presenting with rippling muscles followed by myasthenia gravis are described. Our first patient developed rippling muscles about 1 month after infection with Yersinia enterocolitica. Two years later myasthenia gravis appeared. Our second patient had a 2-year history of asthma prior to the onset of rippling muscles which preceded the myasthenic symptoms by 4-8 weeks. Acetylcholine receptor and anti-skeletal muscle antibody titers were positive in both patients. In both patients the rippling phenomena worsened with pyridostigmine treatment but markedly improved after immunosuppression with azathioprine.

Borrelia burgdorferi myositis: report of eight patients.

Myositis is a rare manifestation of Lyme disease of unknown pathogenesis. This study describes the course of disease in eight patients with Lyme disease, aged 37-70 years, all of whom were suffering from histologically proven myositis. The clinical, electrophysiological, and myopathological findings are reported. One patient showed signs and symptoms of myositis of all limbs. In six patients myositis was localized in the vicinity of skin lesions, arthritis or neuropathy caused by Borrelia burgdorferi. In another patient suffering from pronounced muscle weakness of the legs and cardiac arrest, inflammation of the myocardium, the conducting system and skeletal muscles was revealed at autopsy. Muscle biopsy revealed lymphoplasmocellular infiltrates combined with few fibre degenerations in three patients. The lymphoplasmocellular infiltrates were found predominantly in the vicinity of small vessels. Several spirochetes were stained in six of seven muscle biopsy samples by means of the immunogold-silver technique. Culturing of B. Burgdorferi from the muscle biopsy samples was, however, unsuccessful. Antibiotic treatment succeeded in curing the myositis in four of six patients. In one patients signs and symptoms improved. One patient died from cardiac arrest caused by myocarditis and Guillain-Barré syndrome. The outcome is unknown in one patient. Clinical and myopathological findings indicate that Lyme myositis can be caused either by local spreading of B. burgdorferi or an unknown antigen or toxin from adjacent tissues or haematogenously.