SMN2 splice modulators enhance U1-pre-mRNA association and rescue SMA mice.

Spinal muscular atrophy (SMA), which results from the loss of expression of the survival of motor neuron-1 (SMN1) gene, represents the most common genetic cause of pediatric mortality. A duplicate copy (SMN2) is inefficiently spliced, producing a truncated and unstable protein. We describe herein a potent, orally active, small-molecule enhancer of SMN2 splicing that elevates full-length SMN protein and extends survival in a severe SMA mouse model. We demonstrate that the molecular mechanism of action is via stabilization of the transient double-strand RNA structure formed by the SMN2 pre-mRNA and U1 small nuclear ribonucleic protein (snRNP) complex. The binding affinity of U1 snRNP to the 5' splice site is increased in a sequence-selective manner, discrete from constitutive recognition. This new mechanism demonstrates the feasibility of small molecule-mediated, sequence-selective splice modulation and the potential for leveraging this strategy in other splicing diseases.

Large genomic deletions: a novel cause of Ullrich congenital muscular dystrophy.

Two mutational mechanisms are known to underlie Ullrich congenital muscular dystrophy (UCMD): heterozygous dominant negatively-acting mutations and recessively-acting loss-of-function mutations. We describe large genomic deletions on chromosome 21q22.3 as a novel type of mutation underlying recessively inherited UCMD in 2 families. Clinically unaffected parents carrying large genomic deletions of COL6A1and COL6A2also provide conclusive evidence that haploinsufficiency for COL6A1and COL6A2is not a disease mechanism for Bethlem myopathy. Our findings have important implications for the genetic evaluation of patients with collagen VI-related myopathies as well as for potential therapeutic interventions for this patient population.

Lower leg muscle involvement in Duchenne muscular dystrophy: an MR imaging and spectroscopy study.

OBJECTIVE: To describe the involvement of lower leg muscles in boys with Duchenne muscular dystrophy (DMD) by using MR imaging (MRI) and spectroscopy (MRS) correlated to indices of functional status. SUBJECTS AND METHODS: Nine boys with DMD (mean age, 11 years) and eight healthy age- and BMI-matched boys (mean age, 13 years) prospectively underwent lower leg MRI, 1H-MRS of tibialis anterior (TA) and soleus (SOL) for lipid fraction measures, and 31P-MRS for pH and high-energy phosphate measures. DMD subjects were evaluated using the Vignos lower extremity functional rating, and tests including 6 min walk test (6MWT) and 10 m walk. RESULTS: DMD subjects had highest fatty infiltration scores in peroneal muscles, followed by medial gastrocnemius and soleus. Compared to controls, DMD boys showed higher intramuscular fat (P = 0.04), lipid fractions of TA and SOL (P = 0.02 and 0.003, respectively), pH of anterior compartment (P = 0.0003), and lower phosphocreatine/inorganic phosphorus ratio of posterior compartment (P = 0.02). The Vignos rating correlated with TA (r = 0.79, P = 0.01) and SOL (r = 0.71, P = 0.03) lipid fractions. The 6MWT correlated with fatty infiltration scores of SOL (r = -0.76, P = 0.046), medial (r = -0.80, P = 0.03) and lateral (r = -0.84, P = 0.02) gastrocnemius, intramuscular fat (r = -0.80, P = 0.03), and SOL lipid fraction (r = -0.89, P = 0.007). Time to walk 10 m correlated with anterior compartment pH (r = 0.78, P = 0.04). CONCLUSION: Lower leg muscles of boys with DMD show a distinct involvement pattern and increased adiposity that correlates with functional status. Lower leg MRI and 1H-MRS studies may help to noninvasively demonstrate the severity of muscle involvement.

Automated drug screening with contractile muscle tissue engineered from dystrophic myoblasts.

Identification of factors that improve muscle function in boys with Duchenne muscular dystrophy (DMD) could lead to an improved quality of life. To establish a functional in vitro assay for muscle strength, mdx murine myoblasts, the genetic homologue of DMD, were tissue engineered in 96-microwell plates into 3-dimensional muscle constructs with parallel arrays of striated muscle fibers. When electrically stimulated, they generated tetanic forces measured with an automated motion tracking system. Thirty-one compounds of interest as potential treatments for patients with DMD were tested at 3 to 6 concentrations. Eleven of the compounds (insulin-like growth factor-1, creatine, beta-hydroxy-beta-methylbutyrate, trichostatin A, lisinopril, and 6 from the glucocorticoid family) significantly increased tetanic force relative to placebo-treated controls. The glucocorticoids methylprednisolone, deflazacort, and prednisone increased tetanic forces at low doses (EC(50) of 6, 19, and 56 nM, respectively), indicating a direct muscle mechanism by which they may be benefitting DMD patients. The tetanic force assay also identified beneficial compound interactions (arginine plus deflazacort and prednisone plus creatine) as well as deleterious interactions (prednisone plus creatine inhibited by pentoxifylline) of combinatorial therapies taken by some DMD patients. Since mdx muscle in vivo and DMD patients respond in a similar manner to many of these compounds, the in vitro assay will be a useful tool for the rapid identification of new potential treatments for muscle weakness in DMD and other muscle disorders.

Upregulation of the creatine synthetic pathway in skeletal muscles of mature mdx mice.

Duchenne muscular dystrophy (DMD) is a fatal neuromuscular human disease caused by dystrophin deficiency. The mdx mouse lacks dystrophin protein, yet does not exhibit the debilitating DMD phenotype. Investigating compensatory mechanisms in the mdx mouse may shed new insights into modifying DMD pathogenesis. This study targets two metabolic genes, guanidinoacetate methyltransferase (GAMT) and arginine:glycine amidinotransferase (AGAT) which are required for creatine synthesis. We show that GAMT and AGAT mRNA are up-regulated 5.4- and 1.9-fold respectively in adult mdx muscle compared to C57. In addition, GAMT protein expression is up-regulated at least 2.5-fold in five different muscles of mdx vs. control. Furthermore, we find GAMT immunoreactivity in up to 80% of mature mdx muscle fibers in addition to small regenerating fibers and rare revertants; while GAMT immunoreactivity is equal to background levels in all muscle fibers of mature C57 mice. The up-regulation of the creatine synthetic pathway may help maintain muscle creatine levels and limit cellular energy failure in leaky mdx skeletal muscles. These results may help better understand the mild phenotype of the mdx mouse and may offer new treatment horizons for DMD.

An 18-year-old man with fenestrated vertebral arteries, recurrent stroke and successful angiographic coiling.

Fenestration of vertebral arteries has been reported in association with thromboembolic brain infarctions. However, few cases have been reported in which recurrent infarction occurred in spite of adequate anticoagulation. We report a young man with fenestrated vertebral arteries and stroke who failed to respond to standard anticoagulation therapy but did well with angiographic coil obliteration of an abnormal vertebral segment. An 18-year-old left-handed man presented with acute onset of dizziness and headache. No trauma or other stroke risk factors were identified. Left cerebellar infarction was seen on CT, but the cause could not be identified by brain and neck MRI, MRA, or CTA. Bilateral fenestrated vertebral arteries were identified with conventional angiography. Although the patient recovered fully and was treated with anticoagulation, he suffered a recurrent stroke 1 month later involving the right cerebellum while he was on a therapeutic dose of warfarin. Repeat arteriography showed a spontaneous dissection within one of the fenestrated vertebral segments. Since receiving angiographic coil obliteration of the pathologic segment, he has been free of all symptoms. We conclude that the patient sustained recurrent thromboembolic events in his posterior circulation due to spontaneous dissection within a fenestrated vertebral artery segment. Conventional angiography and emergent interventional embolization were essential to his diagnostic evaluation and therapeutic intervention.

Neuromyelitis optica immunoglobulin G in a child.

Neuromyelitis optica or Devic's syndrome is an uncommon demyelinating disorder that preferentially attacks the spinal cord and optic nerves. Although it is well described in adults, childhood neuromyelitis optica has rarely been reported in the literature and is frequently misdiagnosed as severe multiple sclerosis. Recently, a serum immunoglobulin G test for neuromyelitis optica has become available which may clarify and accelerate the diagnosis. This report describes a child with recurrent myelitis and an elongated spinal cord lesion who was found to have positive neuromyelitis optica autoantibody. We believe that neuromyelitis optica autoantibody testing should be performed in cases of pediatric transverse myelitis with multiple vertical segments or recurrence.

Febrile seizure: measuring adherence to AAP guidelines among community ED physicians.

OBJECTIVE: In 1996, the American Academy of Pediatrics published practice parameters for the acute management of febrile seizure. These guidelines emphasize the typically benign nature of the condition and discourage aggressive neurodiagnostic evaluation. The extent to which these suggestions have been adopted by general emergency medicine practitioners is unknown. We sought to describe recent patterns of the emergency department (ED) evaluation of febrile seizures with respect to these parameters. METHODS: A retrospective review of records of children between 6 month and 6 years of age diagnosed with "febrile seizure" (International Classification of Diseases, Ninth Revision, Clinical Modification 780.31) at 42 community hospital general EDs nationwide was performed. Electronic records of an ED physician billing service from October 2002 to September 2003 were used to identify relevant records. Data had been entered into a proprietary template documentation system, and all charts were reviewed by a professional coder blinded to outcomes of interest. Rates of resource utilization (including lumbar puncture, radiography, hospital admission) were noted. RESULTS: A total of 1029 charts met inclusion criteria. The overall rate of lumbar puncture was 5.2%, and variations were strongly associated with age (8.4% <18 months old vs 3.3% >18 months old). This low rate and age discrimination were consistent with the guidelines of the American Academy of Pediatrics. Although not recommended in the routine evaluation of febrile seizure, computed tomography was part of the evaluation in 11%. The overall rate of admissions or transfers was 12%. CONCLUSIONS: Six years after publication of practice parameters, the use of lumbar puncture in the evaluation of febrile seizure is uncommon and most patients are discharged home. However, the relatively frequent use of head computed tomography is inconsistent with these practice guidelines and merits further investigation.

Mortality and Causes of Death in Patients with Sporadic Inclusion Body Myositis: Survey Study Based on the Clinical Experience of Specialists in Australia, Europe and the USA.

BACKGROUND: There is a paucity of data on mortality and causes of death (CoDs) in patients with sporadic inclusion body myositis (sIBM), a rare, progressive, degenerative, inflammatory myopathy that typically affects those aged over 50 years. OBJECTIVE: Based on patient records and expertise of clinical specialists, this study used questionnaires to evaluate physicians' views on clinical characteristics of sIBM that may impact on premature mortality and CoDs in these patients. METHODS: Thirteen physicians from seven countries completed two questionnaires online between December 20, 2012 and January 15, 2013. Responses to the first questionnaire were collated and presented in the second questionnaire to seek elaboration and identify consensus. RESULTS: All 13 physicians completed both questionnaires, providing responses based on 585 living and 149 deceased patients under their care. Patients were reported to have experienced dysphagia (60.2%) and injurious falls (44.3%) during their disease. Over half of physicians reported that a subset of their patients with sIBM had a shortened lifespan (8/13), and agreed that bulbar dysfunction/dysphagia/oropharyngeal involvement (12/13), early-onset disease (8/13), severe symptoms (8/13), and falls (7/13) impacted lifespan. Factors related to sIBM were reported as CoDs in 40% of deceased patients. Oropharyngeal muscle dysfunction was ranked as the leading feature of sIBM that could contribute to death. The risk of premature mortality was higher than the age-matched comparison population. CONCLUSIONS: In the absence of data from traditional sources, this study suggests that features of sIBM may contribute to premature mortality and may be used to inform future studies.

Truncal fat distribution correlates with decreased vital capacity in Duchenne muscular dystrophy.

BACKGROUND: Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder associated with progressive muscle weakness and respiratory failure. Oral corticosteroids are the mainstay of treatment, but are associated with obesity with a central distribution. This study is designed to determine the relationship between body mass index, central adiposity, and lung function in subjects with DMD. METHODS: Retrospective fat distribution data was obtained in boys with DMD from studies using dual X-ray absorptiometry (DXA). Fat distribution data was reviewed at two tertiary academic institutions and compared with concurrent height, weight, body mass index (BMI), measures of lung function, and sleep study data when available. Truncal fat mass used as a measure of central adiposity. RESULTS: Forty-four subjects (age 12.0 ± 3.4 years) were included. Mean BMI was 22.1 ± 5.9 kg/m(2) . Sixty-eight percent (30 patients) were on corticosteroid therapy. Truncal fat mass percentage was inversely correlated with forced vital capacity (% predicted FVC) (Pearson coefficient -0.37, P = 0.01). Linear regression showed that truncal fat distribution, but not total fat mass, age or corticosteroid use negatively predicted FVC (r(2) = 0.24, P = 0.048). BMI had a positive effect (P = 0.04). However, fat distribution did not predict the rate of change of lung function in a smaller sample. Fat distribution, BMI, or age did not predict measures of sleep disordered breathing. CONCLUSIONS: Truncal fat distribution is a significant predictor of lower vital capacity in boys with DMD, whereas BMI has a positive effect.

Treatment of sporadic inclusion body myositis with bimagrumab.

OBJECTIVE: To study activin signaling and its blockade in sporadic inclusion body myositis (sIBM) through translational studies and a randomized controlled trial. METHODS: We measured transforming growth factor ß signaling by SMAD2/3 phosphorylation in muscle biopsies of 50 patients with neuromuscular disease (17 with sIBM). We tested inhibition of activin receptors IIA and IIB (ActRII) in 14 patients with sIBM using one dose of bimagrumab (n = 11) or placebo (n = 3). The primary outcome was the change in right thigh muscle volume by MRI at 8 weeks. Lean body mass, strength, and function were secondary outcomes. Twelve of the patients (10 bimagrumab, 2 placebo) participated in a subsequent 16-week observation phase. RESULTS: Muscle SMAD2/3 phosphorylation was higher in sIBM than in other muscle diseases studied (p = 0.003). Eight weeks after dosing, the bimagrumab-treated patients increased thigh muscle volume (right leg +6.5% compared with placebo, p = 0.024; left leg +7.6%, p = 0.009) and lean body mass (+5.7% compared with placebo, p = 0.014). Subsequently, bimagrumab-treated patients had improved 6-minute walking distance, which peaked at 16 weeks (+14.6%, p = 0.008) compared with placebo. There were no serious adverse events; the main adverse events with bimagrumab were mild acne and transient involuntary muscle contractions. CONCLUSIONS: Transforming growth factor ß superfamily signaling, at least through ActRII, is implicated in the pathophysiology of sIBM. Inhibition of ActRII increased muscle mass and function in this pilot trial, offering a potential novel treatment of sIBM. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that for patients with inclusion body myositis, bimagrumab increases thigh muscle volume at 8 weeks.

Muscle-Eye-Brain disease.

A term female infant was evaluated for global developmental delay, hypotonia, hyporeflexia, diffuse weakness including facial muscles, and visual impairment with optic nerve hypoplasia. In the absence of family history or perinatal concerns, an extensive investigation was performed, including lab studies, muscle biopsy, brain MRI and focused genetic testing. This revealed elevated serum CK, a structurally abnormal brain, and a dystrophic-appearing muscle biopsy with evidence of a glycosylation defect in the alpha-dystroglycan complex. Of the 6 known related genes, testing of the POMGnT1 gene showed three heterozygous missense mutations. Thus her history, examination, biopsy specimen, imaging, laboratory, and genetic studies are all consistent with the diagnosis of Muscle-Eye-Brain (MEB) disease. MEB is one of an emerging spectrum of congenital disorders that involve both central and peripheral nervous systems, described further in this case report.

The Dietary Supplement Protandim Decreases Plasma Osteopontin and Improves Markers of Oxidative Stress in Muscular Dystrophy Mdx Mice.

Therapeutic options for Duchenne muscular dystrophy (DMD), the most common and lethal neuromuscular disorder in children, remain elusive. Oxidative damage is implicated as a pertinent factor involved in its pathogenesis. Protandim((R)) is an over-the-counter supplement with the ability to induce antioxidant enzymes. In this study we investigated whether Protandim((R)) provided benefit using surrogate markers and functional measures in the dystrophin-deficient (mdx)mouse model of DMD. Male 3-week-old mdx mice were randomized into two treatment groups: control (receiving standard rodent chow) and Protandim((R))-supplemented standard rodent chow. The diets were continued for 6-week and 6-month studies. The endpoints included the oxidative stress marker thiobarbituric acid-reactive substances (TBARS), plasma osteopontin (OPN), plasma paraoxonase (PON1) activity, H&E histology, gadolinium-enhanced magnetic resonance imaging (MRI) of leg muscle and motor functional measurements. The Protandim((R)) chow diet in mdx mice for 6 months was safe and well tolerated. After 6 months of Protandim((R)), a 48% average decrease in plasma TBARS was seen; 0.92 nmol/mg protein in controls versus 0.48 nmol/mg protein in the Protandim((R)) group (p = .006). At 6 months, plasma OPN was decreased by 57% (p = .001) in the Protandim((R))-treated mice. Protandim((R)) increased the plasma antioxidant enzyme PON1 activity by 35% (p = .018). After 6 months, the mdx mice with Protandim((R)) showed 38% less MRI signal abnormality (p = .07) than mice on control diet. In this 6-month mdx mouse study, Protandim((R)) did not significantly alter motor function nor histological criteria.

Dystrophinopathy presenting with arrhythmia in an asymptomatic 34-year-old man: a case report.

INTRODUCTION: Important clues in the recognition of individuals with dystrophin gene mutations are illuminated in this case report. In particular, this report seeks to broaden the perspective of early signs and symptoms of a potentially life-limiting genetic disorder. This group of disorders is generally considered to be a pediatric muscular dystrophy when in actual fact, this case report may represent a spectrum of subclinically affected adults. CASE PRESENTATION: We present the diagnostic saga of a 34-year-old Caucasian man who had two liver biopsies for elevated liver enzymes and 16 years later presented with a cardiac arrhythmia amidst an emergent appendectomy which finally led to his specific genetic diagnosis. CONCLUSIONS: This genetic disorder can affect more than one organ, and in our patient affected both skeletal and cardiac muscle. Furthermore, liver function tests when elevated may erroneously implicate a liver disorder when they actually reflect cardiac and skeletal muscle origin. Presented here is a patient with Becker's muscular dystrophy and cardiomyopathy.