Duchenne Muscular Dystrophy Males Research Articles

Evaluation of Cardiac, Autonomic Functions in Ambulant Patients with Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD) is an X-linked genetic disorder caused by dystrophin gene mutation resulting in muscle weakness, motor delays, difficulty in standing, and inability to walk by 12 years. As disease progresses, it leads to cardiac and respiratory failure. Evaluation of cardiac autonomic status and echocardiography in DMD patients at a young age can be a potential biomarker to assess disease progression. This study aimed to investigate the younger DMD population of 5-11years of age with mild to moderate cardiac involvement for early detection using non-invasive and cost-effective tools. Genetically confirmed male DMD patients, aged 5-11 years (n = 47), screened from the outpatient department of a tertiary neuroscience institution were subjected to heart rate variability and echocardiographic analysis, and values were correlated with their clinical variables. DMD patients showed a significantly higher difference in HR, interventricular septum, E m/s, and E-wave to A-wave (E/A) ratio than normal values (p < 0.001). Significantly higher HR indicates initial sinus tachycardia and decreased IVD (d), and increased E m/s and E/A ratio mark the onset of cardiac symptoms in DMD patients even though its chamber dimension remains normal and are associated with cardiac muscle fibrosis.

Localized strain characterization of cardiomyopathy in Duchenne muscular dystrophy using novel 4D kinematic analysis of cine cardiovascular magnetic resonance

BackgroundCardiomyopathy (CMP) is the most common cause of mortality in Duchenne muscular dystrophy (DMD), though the age of onset and clinical progression vary. We applied a novel 4D (3D + time) strain analysis method using cine cardiovascular magnetic resonance (CMR) imaging data to determine if localized strain metrics derived from 4D image analysis would be sensitive and specific for characterizing DMD CMP. MethodsWe analyzed short-axis cine CMR image stacks from 43 DMD patients (median age: 12.23 yrs [10.6–16.5]; [interquartile range]) and 25 male healthy controls (median age: 16.2 yrs [13.3–20.7]). A subset of 25 male DMD patients age-matched to the controls (median age: 15.7 yrs [14.0-17.8]) was used for comparative metrics. CMR images were compiled into 4D sequences for feature-tracking strain analysis using custom-built software. Unpaired t-test and receiver operator characteristic area under the curve (AUC) analysis were used to determine statistical significance. Spearman's rho was used to determine correlation. ResultsDMD patients had a range of CMP severity: 15 (35% of total) had left ventricular ejection fraction (LVEF) > 55% with no findings of myocardial late gadolinium enhancement (LGE), 15 (35%) had findings of LGE with LVEF > 55% and 13 (30%) had LGE with LVEF < 55%. The magnitude of the peak basal circumferential strain, basal radial strain, and basal surface area strain were all significantly decreased in DMD patients relative to healthy controls (p < 0.001) with AUC values of 0.80, 0.89, and 0.84 respectively for peak strain and 0.96, 0.91, and 0.98 respectively for systolic strain rate. Peak basal radial strain, basal radial systolic strain rate, and basal circumferential systolic strain rate magnitude values were also significantly decreased in mild CMP (No LGE, LVEF > 55%) compared to a healthy control group (p< 0.001 for all). Surface area strain significantly correlated with LVEF and extracellular volume (ECV) respectively in the basal (rho = − 0.45, 0.40), mid (rho = − 0.46, 0.46), and apical (rho = − 0.42, 0.47) regions. ConclusionStrain analysis of 3D cine CMR images in DMD CMP patients generates localized kinematic parameters that strongly differentiate disease from control and correlate with LVEF and ECV.

Wechsler Scale Intelligence Testing in Males with Dystrophinopathies: A Review and Meta-Analysis.

Intelligence scores in males with Duchenne Muscular Dystrophy (DMD) and Becker Muscular Dystrophy (BMD) remain a major issue in clinical practice. We performed a literature review and meta-analysis to further delineate the intellectual functioning of dystrophinopathies. Published, peer-reviewed articles assessing intelligence, using Wechsler Scales, of males with DMD or BMD were searched from 1960 to 2022. Meta-analysis with random-effects models was conducted, assessing weighted, mean effect sizes of full-scale IQ (FSIQ) scores relative to normative data (Mean = 100, Standard Deviation = 15). Post hoc we analysed differences between performance and verbal intelligence scores. 43 studies were included, reporting data on 1472 males with dystrophinopathies; with FSIQ scores available for 1234 DMD (k = 32) and 101 BMD (k = 7). DMD males score, on average, one standard deviation below average (FSIQ = 84.76) and significantly lower than BMD (FSIQ = 92.11). Compared to a previous meta-analysis published in 2001, we find, on average, significantly higher FSIQ scores in DMD. Males with Duchenne have, on average, significantly lower FSIQ scores than BMD males and the general population. Clinicians must consider lower intelligence in dystrophinopathies to ensure good clinical practice.

SNTA1 gene rescues ion channel function and is antiarrhythmic in cardiomyocytes derived from induced pluripotent stem cells from muscular dystrophy patients.

Patients with cardiomyopathy of Duchenne Muscular Dystrophy (DMD) are at risk of developing life-threatening arrhythmias, but the mechanisms are unknown. We aimed to determine the role of ion channels controlling cardiac excitability in the mechanisms of arrhythmias in DMD patients. To test whether dystrophin mutations lead to defective cardiac NaV1.5-Kir2.1 channelosomes and arrhythmias, we generated iPSC-CMs from two hemizygous DMD males, a heterozygous female, and two unrelated control males. We conducted studies including confocal microscopy, protein expression analysis, patch-clamping, non-viral piggy-bac gene expression, optical mapping and contractility assays. Two patients had abnormal ECGs with frequent runs of ventricular tachycardia. iPSC-CMs from all DMD patients showed abnormal action potential profiles, slowed conduction velocities, and reduced sodium (INa) and inward rectifier potassium (IK1) currents. Membrane NaV1.5 and Kir2.1 protein levels were reduced in hemizygous DMD iPSC-CMs but not in heterozygous iPSC-CMs. Remarkably, transfecting just one component of the dystrophin protein complex (α1-syntrophin) in hemizygous iPSC-CMs from one patient restored channelosome function, INa and IK1 densities, and action potential profile in single cells. In addition, α1-syntrophin expression restored impulse conduction and contractility and prevented reentrant arrhythmias in hiPSC-CM monolayers. We provide the first demonstration that iPSC-CMs reprogrammed from skin fibroblasts of DMD patients with cardiomyopathy have a dysfunction of the NaV1.5-Kir2.1 channelosome, with consequent reduction of cardiac excitability and conduction. Altogether, iPSC-CMs from patients with DMD cardiomyopathy have a NaV1.5-Kir2.1 channelosome dysfunction, which can be rescued by the scaffolding protein α1-syntrophin to restore excitability and prevent arrhythmias. Supported by National Institutes of Health R01 HL122352 grant; 'la Caixa' Banking Foundation (HR18-00304); Fundación La Marató TV3: Ayudas a la investigación en enfermedades raras 2020 (LA MARATO-2020); Instituto de Salud Carlos III/FEDER/FSE; Horizon 2020 - Research and Innovation Framework Programme GA-965286 to JJ; the CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the Ministerio de Ciencia e Innovación (MCIN) and the Pro CNIC Foundation), and is a Severo Ochoa Center of Excellence (grant CEX2020-001041-S funded by MICIN/AEI/10.13039/501100011033). American Heart Association postdoctoral fellowship 19POST34380706s to JVEN. Israel Science Foundation to OB and MA [824/19]. Rappaport grant [01012020RI]; and Niedersachsen Foundation [ZN3452] to OB; US-Israel Binational Science Foundation (BSF) to OB and TH [2019039]; Dr. Bernard Lublin Donation to OB; and The Duchenne Parent Project Netherlands (DPPNL 2029771) to OB. National Institutes of Health R01 AR068428 to DM and US-Israel Binational Science Foundation Grant [2013032] to DM and OB.

Development of a novel startle response task in Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD), an X-linked childhood-onset muscular dystrophy caused by loss of the protein dystrophin, can be associated with neurodevelopmental, emotional and behavioural problems. A DMD mouse model also displays a neuropsychiatric phenotype, including increased startle responses to threat which normalise when dystrophin is restored in the brain. We hypothesised that startle responses may also be increased in humans with DMD, which would have potential translational therapeutic implications. To investigate this, we first designed a novel discrimination fear-conditioning task and tested it in six healthy volunteers, followed by male DMD (n = 11) and Control (n = 9) participants aged 7-12 years. The aims of this methodological task development study were to: i) confirm the task efficacy; ii) optimise data processing procedures; iii) determine the most appropriate outcome measures. In the task, two neutral visual stimuli were presented: one 'safe' cue presented alone; one 'threat' cue paired with a threat stimulus (aversive noise) to enable conditioning of physiological startle responses (skin conductance response, SCR, and heart rate). Outcomes were the unconditioned physiological startle responses to the initial threat, and retention of conditioned responses in the absence of the threat stimulus. We present the protocol development and optimisation of data processing methods based on empirical data. We found that the task was effective in producing significantly higher physiological startle SCR in reinforced 'threat' trials compared to 'safe' trials (P < .001). Different data extraction methods were compared and optimised, and the optimal sampling window was derived empirically. SCR amplitude was the most effective physiological outcome measure when compared to SCR area and change in heart rate, with the best profile on data processing, the least variance, successful conditioned response retention (P = .01) and reliability assessment in test-retest analysis (rho = .86). The definition of this novel outcome will allow us to study this response in a DMD population.

Major Adverse Dystrophinopathy Event Score as Marker of Cumulative Morbidity and Risk for Mortality in Boys with Duchenne Muscular Dystrophy

<h3>Purpose</h3> Accurate assessments of heart failure (HF) severity in Duchenne Muscular Dystrophy (DMD) is challenging due to overlapping symptoms from cardiomyopathy, respiratory insufficiency, and skeletal myopathy. We developed an ordinal scale of multiorgan clinical variables and events graded for severity that reflect cumulative disease burden-the <b>M</b>ajor <b>A</b>dverse <b>D</b>ystrophinopathy <b>E</b>vent <b>(MADE</b>) score. We hypothesized that a higher MADE score would be associated with increased mortality in DMD. We used the CINRG Duchenne Natural History Study (DNHS) dataset for MADE score validation. <h3>Methods</h3> DNHS variables were selected based on clinical relevance to prespecified MADE domains: Cardiac, Pulmonary, Myopathy, Nutrition. Severity points (0-4) were assigned and summed for study visits. MADE score for cohorts defined by age, ambulatory status, and survival were compared at enrollment and serially. Ability of baseline MADE score to predict mortality that occurred during the DNHS was examined. <h3>Results</h3> DNHS enrolled 440 males, 12.6 ± 6.1 years old, followed for 3,559 study visits over 4.6 ± 2.8 years, with 45 deaths. MADE score increased with age and was higher in the nonambulatory cohort. Effect of Cardiac and Pulmonary domains on total Score over time doubled and tripled respectively for nonambulatory vs ambulatory cohorts (p<.001). Mean MADE score per visit was 19 ± 10 for those who died vs. 9.8 ± 9.3 in survivors p=0.03. A baseline MADE score >12 predicted mortality independent of age (78% sensitivity, CPE.70). A rising MADE score trajectory was associated with mortality in models adjusted for enrollment age, follow-up time, and ambulatory status, all p<.001<b>.</b> Figure <h3>Conclusion</h3> A multiorgan severity score, MADE, was developed to track cumulative morbidities that impact HF in DMD. MADE score, independent of age, predicted DNHS mortality. MADE score can be used for serial HF assessment in nonambulatory DMD males and be optimized to serve as an endpoint for DMD clinical research.

Long term treatment with ataluren\u2014the Swedish experience

IntroductionAtaluren is a relatively new treatment for male patients with Duchenne muscular dystrophy (DMD) due to a premature stop codon. Long-term longitudinal data as well as efficacy data on non-ambulant patients are still lacking. Here we present the results from a long-term follow-up study of all DMD patients treated with ataluren and followed at the Queen Silvia Children’s Hospital in Gothenburg, Sweden, with focus on the evolution of patients’ upper motor and respiratory function over time.MethodsThis is a retrospective longitudinal case-series study of all male DMD patients treated with ataluren and followed at the Queen Silvia Children’s Hospital in Gothenburg, Sweden, since 2008.ResultsOur eleven patients had a median exposure to ataluren of 2312 days which is almost a fourfold higher than previous studies. Loss of ambulation occurred at a median age of 13.2 years. Patients who lost ambulation prior to 13.2 years of age had received ataluren for 5 years, whereas patients who continued to be ambulatory after 13.2 years of age had received ataluren for 6.5 years until loss of ambulation or last follow-up if still ambulatory. Four of six non ambulatory patients had Performance of the Upper Limb scores above the expected mean values over time. All but one patient maintained a pulmonary decline above the expected over time. All ambulatory patients increased in their predicted forced vital capacity (FVC) with 2.8 to 8.2% annually. Following loss of ambulation, 5 of 6 patients declined in predicted FVC (%), with annual rate of decline varying from 1.8 to 21.1%. The treatment was safe and well tolerated throughout the follow-up period.ConclusionsThis is the first study to present long-term cumulative treatment outcomes over a median period of 6.3 years on ataluren treatment. Our results indicate a delay in loss of ambulation, as well as a slower decline in FVC and upper limb motor function even after loss of ambulation. We suggest that treatment with ataluren should be initiated as soon as the diagnosis is confirmed, closely monitored and, in case of sustainable benefit, continued even after loss of ambulation.

“Pulmonary dysfunction in children with Duchenne muscular dystrophy may appear earlier than we thought – analysis using novel methodology based on z-scores."

IntroductionRespiratory status is one of the main factors affecting the length of survival in patients with Duchenne muscular dystrophy (DMD) – the most common, severe, progressive muscular dystrophy.The aim: (1) to assess pulmonary function in DMD patients using the z-score method and (2) to identify factors affecting it, irrespective of the disease progress.Material and methodsWe evaluated 55 boys (aged 5 – 18 years) with DMD. The spirometry was performed with: forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak expiratory flow (PEF) analysis as absolute values (in litres or litres/min), % predicted value (%pv) and z-scores [z]. The need of ventilation support, ambulatory status, steroid therapy were collected.Results25(45%) subjects were non-ambulatory, 38(69%) used steroid therapy. Mean FVC[z] -2.4±2.2, FEV1[z] -2.0±1.9, PEF[z] -1.5±1.3 value significantly decrease with age (r=-0.62/-0.65/-0.55; p&lt;0.001 respectively), after reaching the peak values between 9-12 or 6-9 years of age depending on analysis method (absolute, %pv or z-score). The results fell below normal range (z-score&lt;-1.64) at the age of 9.8/10.4/11.6 years and below 80%pv at 10.7/13.2/13.2 for FVC/FEV1/PEF, respectively. The pulmonary function test results were significantly lower in non-ambulant (p&lt;0.001) and non-steroid patients (p&lt;0.02).ConclusionsAnalysis of pulmonary function test based on z-score shows that deterioration of pulmonary function in DMD males may appear earlier than we thought measured by %pv and absolute values. Early loss of ambulation, lack of or delayed steroid therapy are risk factors for worse pulmonary outcomes. To confirm these findings cohort longitudinal studies are necessary.

Abstract 15784: Left Ventricular Structural Remodeling and Cardiomyopathy in Duchenne Muscular Dystrophy Carriers

Introduction: Duchenne muscular dystrophy (DMD) is an X-linked neuromuscular disorder. DMD-associated cardiomyopathy is the primary mode of premature death in the majority of male DMD patients, but the prevalence of cardiomyopathy and its clinical significance in female DMD carriers is less well characterized. Hypothesis: We hypothesized that a significant proportion of DMD carriers develop maladaptive left ventricular (LV) structural remodeling and cardiomyopathy over time. Methods: A cross-sectional study was undertaken comparing cardiac magnetic resonance imaging (cMRI) and cardiopulmonary stress test (CPX) parameters between DMD carriers and healthy age- and sex-matched controls from the Dallas Heart Study (DHS). Demographic data, cMRI parameters, and CPX parameters were collected retrospectively on 30 consecutive DMD carriers and 26 control DHS subjects. Results: Overall, DMD carriers had a significantly lower LVEF compared to DHS controls (58+8% vs 70+7%, p&lt; 0.0001). The overall prevalence of reduced LVEF in DMD carriers (defined as LVEF &lt;60%) was 63% compared to 8% in DHS controls. The volumetric variables indexed to body surface area (LVEDVi and LVESVi) were significantly higher in DMD carriers compared to control subjects (72+14 ml/m 2 vs 58+7, p&lt; 0.0001; 31+10 ml/m 2 vs 17+5, p&lt; 0.0001; respectively). LV concentricity was also significantly lower among all DMD carriers compared to DHS controls (3.10+0.65 g/mL 0.67 vs 3.73+0.79, p =0.002). LV concentricity was significantly lower in DMD carriers with reduced EF compared to controls (3.09+0.51 g/mL 0.67 vs 3.73+0.79, p = 0.012), while DMD carriers with preserved EF also had reduced concentricity compared to controls (3.12+0.86 vs 3.73+0.79, p = 0.054). Finally, peak VO 2 was lower in DMD carriers compared to DHS controls (23+6 ml/kg/min vs 25+4, p =0.076), though this difference did not reach statistical significance. Conclusions: Collectively, the data suggest that middle-aged female DMD carriers are at greater risk of developing left ventricular systolic dysfunction and cardiomyopathy associated with decreased exercise capacity. A possible mechanism driving the development of this cardiomyopathy is progressive, maladaptive left ventricular dilatation and cardiac atrophy.

Comprehensive genetic analysis of 961 unrelated Duchenne Muscular Dystrophy patients: Focus on diagnosis, prevention and therapeutic possibilities.

Recently DNA sequencing analysis has played a vital role in the unambiguous diagnosis of clinically suspected patients with Duchenne Muscular Dystrophy (DMD). DMD is a monogenic, X-linked, recessive, degenerative pediatric neuromuscular disorder affecting males, invariably leading to fatal cardiopulmonary failure. Early and precise diagnosis of the disease is an essential part of an effective disease management strategy as care guidelines and prevention through counseling need to be initiated at the earliest particularly since therapies are now available for a subset of patients. In this manuscript we report the DMD gene mutational profiles of 961 clinically suspected male DMD patients, 99% of whom were unrelated. We utilized a molecular diagnostic approach which is cost-effective for most patients and follows a systematic process that sequentially involves identification of hotspot deletions using mPCR, large deletions and duplications using MLPA and small insertions/ deletions and point mutations using an NGS muscular dystrophy gene panel. Pathogenic DMD gene mutations were identified in 84% of patients. Our data compared well with the frequencies and distribution of deletions and duplications reported in the DMD gene in other published studies. We also describe a number of rare in-frame mutations, which appeared to be enriched in the 5’ proximal hotspot region of the DMD gene. Furthermore, we identified a family with a rare non-contiguous deletion mutation in the DMD gene where three males were affected and two females were deemed carriers. A subset of patients with mutations in the DMD gene who are likely to benefit therapeutically from new FDA and EMA approved drugs were found in our cohort. Given that the burden of care for DMD patients invariably falls on the mothers, particularly in rural India, effective genetic counseling followed by carrier screening is crucial for prevention of this disorder. We analyzed the carrier status of consented female relatives of 463 probands to gauge the percentage of patients with familial disease. Our analysis revealed 43.7% of mothers with DMD gene mutations. Our comprehensive efforts, involving complete genetic testing coupled with compassionate genetic counseling provided to DMD patients and their families, are intended to improve the quality of life of DMD patients and to empower carrier females to make informed reproductive choices to impede the propagation of this deadly disease.

Utilization of Heart Failure Medications in Duchenne Muscular Dystrophy Patients with Left Ventricular Systolic Dysfunction

Purpose Current guidelines for the management of left ventricular systolic dysfunction (LVSD) in Duchenne Muscular Dystrophy (DMD) recommend angiotensin converting enzyme (ACE) inhibitors (class IIa). Little is known about the historic use of HF medications in Duchenne Muscular Dystrophy (DMD) and LVSD. Methods We performed a retrospective cohort study of DMD patients followed at 17 centers across North America from January 1, 2005-December 31, 2015. LVSD was defined as an ejection fraction (EF) Results LVSD was present in 209/436 (47.9%) DMD males including 84 (19.3%) patients with LVSD on baseline echocardiogram with median age 14 (IQR 11-17). 125 (28.7%) patients developed LVSD during the study with a median age at diagnosis of 15 years (IQR 12-17). Of the 209 patients with LVSD, 48 (23.0%) were never on HF medications, 105 (50.2%), 44 (21.0%), 11 (5.3%) and 1 (0.5%) were on single, dual, triple and quad HF therapy respectively. HF medications prescribed during the study period for those with LVSD included angiotensin converting enzyme inhibitor/angiotensin receptor blocker (ACE/ARB) (134, 64.1%), aldosterone antagonist (17, 8.1%), beta blocker (55, 26.3%), and digoxin (12, 5.7%). 154 (73.7%) were not on heart failure medications at study entry (baseline visit) and first line therapies included ACE/ARB (77, 51.0%), beta blockers (32, 21.2%), aldosterone antagonist (2, 1.3%), and digoxin (6, 4.0%). Overall therapies for these 154 patients included ACE/ARB (84, 55.6%), beta blocker (46, 30.5%), aldosterone antagonist (8, 5.3%) and digoxin (8, 5.3%). Conclusion There is significant practice variability that is not consistent with current consensus guidelines in the utilization of HF medications in DMD patients with LVSD. Almost 65% of the cohort were started on an ACE/ARB, however 23% were never prescribed a HF medication. Further studies are needed within the DMD population to understand the efficacy and decision making related to the prescription of common HF medications.

Bone Health and Endocrine Care of Boys with Duchenne Muscular Dystrophy: Data from the MD STARnet.

Patients with Duchenne muscular dystrophy (DMD) are at high risk of endocrine and bone health complications resulting from the high glucocorticoid (GC) doses used to treat this condition. There are limited data characterizing the clinical management of these complications. To determine the frequency of bone health screening, endocrinologist evaluation, and use of endocrine and bone health pharmacotherapy in the clinical care of males with DMD. A population based cohort study using data from the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet) was conducted. Clinical data was abstracted from the medical records of 683 males with DMD at five surveillance sites across the US. A DXA scan had been documented in 24% of cases; the percentage of cases with DXA varied across surveillance sites from 13% to 43%, p < 0.001. History of fracture and greater disease duration were associated with greater odds of having a DXA. Only 4.7% of cases had documentation of an endocrinologist evaluation. The frequency of documented endocrine and bone health pharmacotherapy use included calcium (42.8%), vitamin D (36.6%), bisphosphonates (13.3%), growth hormone (1.9%), testosterone (1.7%), insulin (1.2%), and metformin (0.3%)Conclusions:A low percentage of DMD males had record of DXA scan, endocrinologist evaluation, or treatment with endocrine or bone health pharmacotherapy. Endocrine and bone health care may represent an unmet need in the DMD population.

Molecular characterization of exonic rearrangements and frame shifts in the dystrophin gene in Duchenne muscular dystrophy patients in a Saudi community

BackgroundIn individuals with Duchenne muscular dystrophy (DMD), exon skipping treatment to restore a wild-type phenotype or correct the frame shift of the mRNA transcript of the dystrophin (DMD) gene are mutation-specific. To explore the molecular characterization of DMD rearrangements and predict the reading frame, we simultaneously screened all 79 DMD gene exons of 45 unrelated male DMD patients using a multiplex ligation-dependent probe amplification (MLPA) assay for deletion/duplication patterns. Multiplex PCR was used to confirm single deletions detected by the MLPA.ResultsThere was an obvious diagnostic delay, with an extremely statistically significant difference between the age at initial symptoms and the age of clinical evaluation of DMD cases (t value, 10.3; 95% confidence interval 5.95–8.80, P < 0.0001); the mean difference between the two groups was 7.4 years. Overall, we identified 147 intragenic rearrangements: 46.3% deletions and 53.7% duplications. Most of the deletions (92.5%) were between exons 44 and 56, with exon 50 being the most frequently involved (19.1%). Eight new rearrangements, including a mixed deletion/duplication and double duplications, were linked to seven cases with DMD. Of all the cases, 17.8% had duplications with no hot spots. In addition, confirmation of the reading frame hypothesis helped account for new DMD rearrangements in this study. We found that 81% of our Saudi patients would potentially benefit from exon skipping, of which 42.9% had a mutation amenable to skipping of exon 51.ConclusionsOur study could generate considerable data on mutational rearrangements that may promote future experimental therapies in Saudi Arabia.

Abstract 415: Transgenic Expression of Dimethylarginine Dimethylaminohydrolase Attenuates Exercise-induced Fatigue in Duchenne Muscular Dystrophy Carrier Mice

Duchenne muscular dystrophy (DMD) is an X-linked disease caused by mutations in dystrophin and characterized by muscle degeneration, cardiomyopathy, and impaired muscle nitric oxide (NO) production that disrupts muscle blood flow regulation and leads to excessive post-exercise fatigue. Interestingly, circulating levels of the endogenous NO synthase inhibitor asymmetric dimethylarginine (ADMA) are elevated in dystrophin-deficient subjects. Therefore, we hypothesized that excessive circulating ADMA impairs muscle NO production and thus negatively impacts exercise tolerance in DMD. The objectives of this study were to determine whether increased circulating ADMA is itself sufficient to affect exercise performance, and whether transgenic modulation of ADMA metabolism could improve exercise-induced fatigue in the mdx mouse model of DMD. Although infusion of exogenous ADMA did impair exercise performance in healthy, wild-type mice, transgenic expression of dimethylarginine dimethylaminohydrolase 1 (DDAH), the enzyme that degrades ADMA, did not affect exercise-induced fatigue in dystrophin-deficient male mdx mice. Surprisingly, DDAH transgene expression did attenuate exercise-induced fatigue in dystrophin-heterozygous female mdx carrier mice. This improvement in exercise tolerance was associated with reduced heart weight, improved cardiac contractile function, and improved chronotropic responsiveness to beta-adrenergic stimulation in DDAH-transgenic female mdx carriers. In contrast, DDAH transgene expression did not significantly affect skeletal muscle pathology in female mdx carriers. We conclude that DDAH transgene expression improves exercise tolerance in dystrophin-heterozygous females, possibly by limiting pathological cardiac remodeling and helping to maintain heart performance. These findings emphasize the importance of methylated arginines to the development of cardiomyopathy in female DMD carriers, and have interesting implications for current genetic therapies that may only partially restore dystrophin expression in the hearts of male DMD patients.

G.P.177: Constipation in Duchenne muscular dystrophy: Common, underdiagnosed and undertreated

Duchenne muscular dystrophy (DMD) is an X-linked progressive degenerative muscle disorder. Constipation as a co-morbidity in DMD has not been subject to a systematic study. To determine the prevalence of constipation, identify its predictive factors and evaluate different screening methods in a cohort of DMD patients. Design/Methods: This was a prospective cross-sectional study that evaluated a cohort of DMD patients for constipation using the pediatric Rome-III questionnaires (QPGS-RIII) and the Bristol stool chart. Additional clinical data collected included functional assessments and medications. Fecal load was assessed on routine spine X-rays. Logistic regression with backward elimination as a variable selection procedure was used to determine possible predictors of constipation. Among 98 male DMD patients (average age 11.3±3.8years), the overall prevalence of constipation fulfilling Rome-III criteria was 44.9%, of which 45% received symptomatic treatment and 11% were asymptomatic. The age distribution of patients with constipation (<i>n</i>=44) was similar to that without (10.8±2.6 vs 11.1±3years, <i>p</i>=0.62). Prevalence of constipation did not correlate with functional status (Northstar ambulatory assessment scale, <i>p</i>=0.39), treatment with calcium supplements (<i>p</i>=0.92) or with stool load on abdominal X-ray (<i>p</i>=0.82). The regression model failed to identify any predictive variables for constipation. The Bristol stool chart, abnormal abdominal exam (fullness, distension, tenderness, palpable masses or abnormal bowel sounds) and fecal load on X-ray were inferior to the Rome-III criteria in diagnosing constipation. (1) Constipation is a common co-morbidity in DMD, irrespective of age or the stage of disease. (2) Of the tests evaluated, the Rome III criteria may be the most appropriate screening tool for constipation in DMD patients. (3) Constipation in this cohort was underdiagnosed and either not treated or treated inadequately.

T.P.12: The performance of upper limb scores correlate with pulmonary function test measures and Egen Klassifikation scores in Duchenne muscular dystrophy

The Performance of Upper Limb module (PUL) was developed as an outcome measure specifically for patients with Duchenne muscular dystrophy (DMD), and is implemented in clinical trials needing longitudinal data. Objectives: The aim of the study was to determine if the PUL score correlate with pulmonary function, cardiac function and Egen Klassifikation (EK) score in non-ambulatory DMD patients on long term glucocorticoid (GC) therapy. The effects of body mass index (BMI) and contractures on PUL scores were also investigated. In this IRB-approved cross-sectional study, 43 non-ambulatory DMD males with mean age ± standard deviation (SD) of 15.7 ± 3.4 years and on long-term GC treatment with mean duration ± SD of 8.9 ± 3.1 years were enrolled and underwent PUL module testing. Their pulmonary function and cardiac function results were analyzed to assess disease progression, and EK scores to assess functional ability. Correlation of BMI and contractures with PUL were also analyzed. The PUL scores had strong correlation with pulmonary function measures at p < 0.01 and had strong inverse correlation with EK scores at p < 0.0001. It had no correlation with left ventricular ejection fraction and left ventricular dysfunction. BMI and the presence of contractures resulting in decreased elbow extension and forearm supination had a negative impact on the total PUL score and was found to be statistically significant at p < 0.05 using paired t-test. We found the PUL module easily applicable in assessing upper extremity function in the DMD population, and correlates well with previously validated functional scale and pulmonary function test measures. The PUL is useful not only in the clinical practice to monitor disease progression and aid in making clinical decisions for care management in this population but is also a relevant outcome measure that can be used in research studies. The Performance of Upper Limb module (PUL) was developed as an outcome measure specifically for patients with Duchenne muscular dystrophy (DMD), and is implemented in clinical trials needing longitudinal data. Objectives: The aim of the study was to determine if the PUL score correlate with pulmonary function, cardiac function and Egen Klassifikation (EK) score in non-ambulatory DMD patients on long term glucocorticoid (GC) therapy. The effects of body mass index (BMI) and contractures on PUL scores were also investigated. In this IRB-approved cross-sectional study, 43 non-ambulatory DMD males with mean age ± standard deviation (SD) of 15.7 ± 3.4 years and on long-term GC treatment with mean duration ± SD of 8.9 ± 3.1 years were enrolled and underwent PUL module testing. Their pulmonary function and cardiac function results were analyzed to assess disease progression, and EK scores to assess functional ability. Correlation of BMI and contractures with PUL were also analyzed. The PUL scores had strong correlation with pulmonary function measures at p < 0.01 and had strong inverse correlation with EK scores at p < 0.0001. It had no correlation with left ventricular ejection fraction and left ventricular dysfunction. BMI and the presence of contractures resulting in decreased elbow extension and forearm supination had a negative impact on the total PUL score and was found to be statistically significant at p < 0.05 using paired t-test. We found the PUL module easily applicable in assessing upper extremity function in the DMD population, and correlates well with previously validated functional scale and pulmonary function test measures. The PUL is useful not only in the clinical practice to monitor disease progression and aid in making clinical decisions for care management in this population but is also a relevant outcome measure that can be used in research studies.

Utility of real-time three-dimensional echocardiography for Duchenne muscular dystrophy with echocardiographic limitations

Duchenne muscular dystrophy (DMD) is strongly associated with a unique form of dilated cardiomyopathy. Cardiac complications are the leading cause of death in DMD; thus, longitudinal assessments and early intervention for cardiac dysfunction are necessary to improve prognosis. Two-dimensional echocardiography, which is routinely used for cardiac assessment, has some limitations for quantitative analyses in DMD patients with thoracic deformities and regional wall motion abnormalities in the left ventricle. Recently, real-time three-dimensional echocardiography has emerged as a feasible tool for cardiac assessment in various cardiac diseases. The aim of this study was to examine the utility of this technology in DMD. We evaluated left ventricular ejection fraction (LVEF), a major parameter of left ventricular function, in 17 male DMD patients. LVEF values measured by real-time three-dimensional echocardiography were compared with those determined by two established nuclear cardiology methods: “the first-pass method of radionuclide angiocardiography” and “quantitative electrocardiogram-gated single-photon emission computed tomography”. A good correlation was observed for LVEF values, particularly between real-time three-dimensional echocardiography and “the first-pass method of radionuclide angiocardiography” (r=0.90, p<0.05). Thus, real-time three-dimensional echocardiography can provide an accurate measurement of LVEF in DMD patients with echocardiographic limitations.

Patterns of Growth in Ambulatory Males with Duchenne Muscular Dystrophy

To provide weight-for-age, height-for-age, and body mass index-for-age growth reference standards for ambulatory, steroid-naïve males, ages 2-12 years, with Duchenne muscular dystrophy (DMD) and to compare these growth curves to the 2000 Centers for Disease Control and Prevention growth charts for boys, which serve as references of physical size and growth for the general male pediatric population in the US. Through a multi-state population-based surveillance of individuals with muscular dystrophy, a total of 1877 weight and 1544 height measurements ascertained during 1985-2010 from 513 males with DMD were obtained retrospectively from medical record review. Cases were classified as DMD if loss of ambulation occurred before the 12th birthday or, if younger than 12 years and still ambulating, the earliest symptoms of dystrophinopathy occurred before the 6th birthday. Each growth chart was constructed using 5 percentiles: 10th, 25th, 50th, 75th, and 90th. Smoothing procedures were applied in 2 stages to the irregular plots of the empirical percentile values. A set of growth curves, derived from a large cohort of male youth with DMD, are presented. These curves demonstrate that DMD males are shorter and tend to the extremes of weight and body mass index compared with the general male pediatric population in the US. Charts representing the pattern of growth in ambulatory, steroid-naïve males with DMD can facilitate monitoring of growth and early detection of unusual growth patterns. Use of these growth standards also will assist in monitoring responses to corticosteroid treatment.

The cooperative international neuromuscular research group Duchenne natural history study: Glucocorticoid treatment preserves clinically meaningful functional milestones and reduces rate of disease progression as measured by manual muscle testing and other commonly used clinical trial outcome measures

introduction: Glucocorticoid (GC) therapy in Duchenne muscular dystrophy (DMD) has altered disease progression, necessitating contemporary natural history studies. The Cooperative Neuromuscular Research Group (CINRG) DMD Natural History Study (DMD-NHS) enrolled 340 DMD males, ages 2-28 years. A comprehensive battery of measures was obtained. A novel composite functional "milestone" scale scale showed clinically meaningful mobility and upper limb abilities were significantly preserved in GC-treated adolescents/young adults. Manual muscle test (MMT)-based calculations of global strength showed that those patients <10 years of age treated with steroids declined by 0.4 ± 0.39 MMT unit/year, compared with -0.4 ± 0.39 MMT unit/year in historical steroid-naive subjects. Pulmonary function tests (PFTs) were relatively preserved in steroid-treated adolescents. The linearity and magnitude of decline in measures were affected by maturational changes and functional status. In DMD, long-term use of GCs showed reduced strength loss and preserved functional capabilities and PFTs compared with previous natural history studies performed prior to the widespread use of GC therapy.

Psychological aspects in children affected by duchenne de boulogne muscular dystrophy.

Impairment of intelligence in Duchenne muscular dystrophy (DMD) patients was described by Duchenne de Boulogne himself in 1868. Further studies report intelligence disorders with mayor impairment of memory. The aim of the present study was to assess the presence of affective and personality disorders in a group of children affected by DMD. Twenty six male DMD patients, mean age eleven and four months years old, were assessed for their affective and personality disorder. Only eight subjects had a total IQ below average with major difficulties in verbal and visual-spatial memory, comprehension, arithmetic and vocabulary. All the subjects presented some disorders: tendency to marginalization and isolation, self-depreciation, sense of insecurity, hypochondriac thoughts and marked state of anxiety. These disorders are often a dynamic prolongation of a psychological process which starts when the diagnosis is made and continues, in a slow and latent fashion, throughout the evolution of the disease.