Linda H. Cripe

Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and pharmacological and psychosocial management

Duchenne muscular dystrophy (DMD) is a severe, progressive disease that affects 1 in 3600-6000 live male births. Although guidelines are available for various aspects of DMD, comprehensive clinical care recommendations do not exist. The US Centers for Disease Control and Prevention selected 84 clinicians to develop care recommendations using the RAND Corporation-University of California Los Angeles Appropriateness Method. The DMD Care Considerations Working Group evaluated assessments and interventions used in the management of diagnostics, gastroenterology and nutrition, rehabilitation, and neuromuscular, psychosocial, cardiovascular, respiratory, orthopaedic, and surgical aspects of DMD. These recommendations, presented in two parts, are intended for the wide range of practitioners who care for individuals with DMD. They provide a framework for recognising the multisystem primary manifestations and secondary complications of DMD and for providing coordinated multidisciplinary care. In part 1 of this Review, we describe the methods used to generate the recommendations, and the overall perspective on care, pharmacological treatment, and psychosocial management.

Diagnosis and management of Duchenne muscular dystrophy, part 2: implementation of multidisciplinary care

Optimum management of Duchenne muscular dystrophy (DMD) requires a multidisciplinary approach that focuses on anticipatory and preventive measures as well as active interventions to address the primary and secondary aspects of the disorder. Implementing comprehensive management strategies can favourably alter the natural history of the disease and improve function, quality of life, and longevity. Standardised care can also facilitate planning for multicentre trials and help with the identification of areas in which care can be improved. Here, we present a comprehensive set of DMD care recommendations for management of rehabilitation, orthopaedic, respiratory, cardiovascular, gastroenterology/nutrition, and pain issues, as well as general surgical and emergency-room precautions. Together with part 1 of this Review, which focuses on diagnosis, pharmacological treatment, and psychosocial care, these recommendations allow diagnosis and management to occur in a coordinated multidisciplinary fashion.

Cardiovascular health supervision for individuals affected by duchenne or becker muscular dystrophy

Duchenne muscular dystrophy is the most common and severe form of the childhood muscular dystrophies. The disease is typically diagnosed between 3 and 7 years of age and follows a predictable clinical course marked by progressive skeletal muscle weakness with loss of ambulation by 12 years of age. Death occurs in early adulthood secondary to respiratory or cardiac failure. Becker muscular dystrophy is less common and has a milder clinical course but also results in respiratory and cardiac failure. The natural history of the cardiomyopathy in these diseases has not been well established. As a result, patients traditionally present for cardiac evaluation only after clinical symptoms become evident. The purpose of this policy statement is to provide recommendations for optimal cardiovascular evaluation to health care specialists caring for individuals in whom the diagnosis of Duchenne or Becker muscular dystrophy has been confirmed.

Circumferential strain analysis identifies strata of cardiomyopathy in Duchenne muscular dystrophy: a cardiac magnetic resonance tagging study.

OBJECTIVES This study sought to evaluate the natural history of occult cardiac dysfunction in Duchenne muscular dystrophy (DMD). BACKGROUND Duchenne muscular dystrophy is characterized by progressive cardiac dysfunction and myocardial fibrosis late in the disease process. We hypothesized that left ventricular myocardial peak circumferential strain (epsilon(cc)) would decrease in DMD before global systolic functional abnormalities regardless of age or ventricular ejection fraction (EF). METHODS We evaluated cardiac magnetic resonance image (MRI) data from 70 DMD patients and 16 aged-matched control subjects. Standard imaging data included steady-state free precession short-axis cine stack images, cine myocardial tagged images, and myocardial delayed enhancement (MDE) (an indicator of myocardial fibrosis) sequences. Analysis was performed with QMASS (Medis Medical Imaging Systems, Leiden, the Netherlands) and HARP (Diagnosoft, Palo Alto, California) software. The DMD patient data were subdivided by age (<10 or >10 years), EF (>55% or <55%), and the presence or absence of MDE. RESULTS The DMD patients with normal EF had reduced epsilon(cc) at an early age (<10 years) compared with control subjects (p < 0.01). The DMD patients age >10 years with normal EF had further decline in epsilon(cc) compared with younger DMD patients (p < 0.01). There was further decline in epsilon(cc) with age in patients with reduced EF (p < 0.01) without MDE. The oldest patients, with both reduced EF and positive MDE, exhibited the lowest epsilon(cc). None of the patients had ventricular hypertrophy. CONCLUSIONS Myocardial strain abnormalities are prevalent in young DMD patients despite normal EF, and these strain values continue to decline with advancing age. Strain analysis in combination with standard MRI and MDE imaging provides a means to stratify DMD cardiomyopathy.

Corticosteroid treatment retards development of ventricular dysfunction in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is characterized by a predictable decline in cardiac function with age that contributes to early death. Although corticosteroids are a clinically effective pharmacologic therapy for skeletal muscle function, there is limited published work documenting the impact on cardiac function. The primary objective of this work is to determine benefit from steroid treatment on the development of ventricular dysfunction in DMD. We performed a historical cohort study of DMD cases undergoing serial cardiac evaluations from 1998-2006. In addition to the history of steroid use, basic medical characteristics and serial echocardiographic measures were obtained for each identified case meeting inclusion criteria. Data from initial (7.5+/-0.8 years) and follow-up (12+/-0.7 years) evaluation was collected from untreated (n=23) and steroid treated (n=14) DMD cases. Kaplan-Meier freedom from ventricular dysfunction was 93% for steroid treated cases versus 53% for untreated cases at 1500 days. Treatment with steroids was protective against ventricular dysfunction (Hazard ratio 0.16 95% CI 0.04, 0.70). We demonstrate here that steroid treatment, begun prior to ventricular dysfunction retards the anticipated development of ventricular dysfunction.

Hypoplastic Left Heart Syndrome Links to Chromosomes 10q and 6q and Is Genetically Related to Bicuspid Aortic Valve

OBJECTIVES This study was designed to identify disease loci for hypoplastic left heart syndrome (HLHS) and evaluate the genetic relationship between HLHS and bicuspid aortic valve (BAV). BACKGROUND Previously, we identified that HLHS and BAV exhibit complex inheritance, and both HLHS and BAV kindreds are enriched for BAV. However, the genetic basis of HLHS and its relationship to BAV remains unclear. METHODS Family-based nonparametric genome-wide linkage analysis was performed in kindreds ascertained by either an HLHS or BAV proband. Echocardiograms were performed on 1,013 participants using a sequential sampling strategy (33 HLHS kindreds, 102 BAV kindreds). RESULTS The recurrence risk ratio of BAV in HLHS families (8.05) was nearly identical to that in BAV families (8.77). Linkage to chromosomal regions 10q22 and 6q23 with maximum logarithm of odds scores of 3.2 and 3.1, respectively, was identified in HLHS kindreds. In addition, 5 suggestive loci were identified (7q31, 11q22, 12q13, 14q23, and 20q11). We previously identified loci at chromosomes 18q22, 13q34, and 5q21 in BAV kindreds. The relationship between these loci was examined in the combined HLHS and BAV cohort and associations between loci were demonstrated (5q21, 13q34, and 14q23; 6q23 and 10q22; 7q31 and 20q11). Subsequent subsets linkage analysis showed a significant improvement in the logarithm of odds score at 14q23 only (4.1, p < 0.0001). CONCLUSIONS These studies demonstrate linkage to multiple loci identifying HLHS as genetically heterogeneous. Subsets linkage analyses and recurrence risk ratios in a combined cohort provide evidence that some HLHS and BAV are genetically related.

Steroid Therapy and Cardiac Function in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy leads to progressive deterioration in skeletal and cardiac muscle function. Steroids prolong ambulation and improve respiratory muscle strength. The authors hypothesized that steroid treatment would stabilize cardiac muscle function. Echocardiograms performed from 1997 to 2004 for 111 subjects 21 years of age or younger with Duchenne muscular dystrophy were restrospectively reviewed. The medical record was reviewed for steroid treatment. Untreated and steroids-treated subjects did not differ in age, height, weight, body mass index, systolic and diastolic blood pressure, or left ventricular mass. The shortening fraction was lower in the untreated group. Of those treated, 29 received prednisone and 19 received deflazacort. There was no difference in the shortening fraction between the two treated subgroups. Treated subjects not receiving steroids still had a normal shortening fraction, which was no different from the shortening fraction of those still receiving treatment. As compared with the treated subjects, the untreated subjects 10 years of age or younger were 4.4 times more likely to have a shortening fraction less than< 28% (p = 0.03), and the untreated subjects older than 10 years were 15.2 times more likely to have a shortening fraction less than< 28% (p < 0.01). This retrospective study suggests that the progressive decline in cardiac function of patients with Duchenne muscular dystrophy can be altered by steroid treatment. The effect appears to be sustained beyond the duration of treatment and independent of steroid type.

Large-scale serum protein biomarker discovery in Duchenne muscular dystrophy

Significance Duchenne muscular dystrophy (DMD) is a rare and devastating muscle disease caused by mutations in the X-linked DMD gene (which encodes the dystrophin protein). Serum biomarkers hold significant potential as objective phenotypic measures of DMD disease state, as well as potential measures of pharmacological effects of and response to therapeutic interventions. Here we describe a proteomics approach to determine serum levels of 1,125 proteins in 93 DMD patients and 45 controls. The study identified 44 biomarkers that differed significantly between patients and controls. These data are being made available to DMD researchers and clinicians to accelerate the search for new diagnostic, prognostic, and therapeutic approaches. Serum biomarkers in Duchenne muscular dystrophy (DMD) may provide deeper insights into disease pathogenesis, suggest new therapeutic approaches, serve as acute read-outs of drug effects, and be useful as surrogate outcome measures to predict later clinical benefit. In this study a large-scale biomarker discovery was performed on serum samples from patients with DMD and age-matched healthy volunteers using a modified aptamer-based proteomics technology. Levels of 1,125 proteins were quantified in serum samples from two independent DMD cohorts: cohort 1 (The Parent Project Muscular Dystrophy–Cincinnati Children’s Hospital Medical Center), 42 patients with DMD and 28 age-matched normal volunteers; and cohort 2 (The Cooperative International Neuromuscular Research Group, Duchenne Natural History Study), 51 patients with DMD and 17 age-matched normal volunteers. Forty-four proteins showed significant differences that were consistent in both cohorts when comparing DMD patients and healthy volunteers at a 1% false-discovery rate, a large number of significant protein changes for such a small study. These biomarkers can be classified by known cellular processes and by age-dependent changes in protein concentration. Our findings demonstrate both the utility of this unbiased biomarker discovery approach and suggest potential new diagnostic and therapeutic avenues for ameliorating the burden of DMD and, we hope, other rare and devastating diseases.

Contemporary Cardiac Issues in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked genetic disorder diagnosed in childhood. It affects ≈1 in every 5000 live male births (≈20 000 new cases worldwide each year).1,2 This results in a US prevalence of 1.3 to 1.8 per 10 000 males 5 to 24 years of age. DMD is caused by mutations in the gene encoding the dystrophin protein. The loss of dystrophin results in a cascade of events leading to progressive loss of muscle function. Without supportive care, young men with DMD typically die in their late teens and early 20s. Historically, the most common cause of death has been respiratory failure. However, with improved respiratory support, an increasingly important source of morbidity and mortality is cardiomyopathy leading to heart failure and arrhythmias.3,4 There are important differences in DMD cardiomyopathy compared with other types of pediatric dilated cardiomyopathy.5 DMD cardiomyopathy is similar to the cardiomyopathy seen in some forms of limb girdle muscular dystrophy and congenital muscular dystrophy. In particular, a shared cardiomyopathic process is seen in those disorders in which the primary mutation alters components that directly or indirectly interact with dystrophin. There is less left ventricular (LV) enlargement at diagnosis in DMD. Only 30% of boys with DMD have cardiac symptoms at diagnosis (far fewer than other dilated cardiomyopathy). DMD cardiomyopathy is less often treated at the time of diagnosis. However, treatment rates have increased over time. Finally, there is a higher mortality for DMD cardiomyopathy than for other dilated cardiomyopathies. The DMD Care Considerations published in 2010 addressed cardiac care recommendations based on minimal surveillance standards with echocardiography.6,7 However, echocardiography has known limitations in DMD patients.8 Since the 2010 publication of the DMD Care Considerations,6,7 there have been significant advances in the understanding …

Eplerenone for early cardiomyopathy in Duchenne muscular dystrophy: a randomised, double-blind, placebo-controlled trial

BACKGROUND Cardiomyopathy is a leading cause of death in patients with Duchenne muscular dystrophy and myocardial damage precedes decline in left ventricular systolic function. We tested the efficacy of eplerenone on top of background therapy in patients with Duchenne muscular dystrophy with early myocardial disease. METHODS In this randomised, double-blind, placebo-controlled trial, boys from three centres in the USA aged 7 years or older with Duchenne muscular dystrophy, myocardial damage by late gadolinium enhancement cardiac MRI and preserved ejection fraction received either eplerenone 25 mg or placebo orally, every other day for the first month and once daily thereafter, in addition to background clinician-directed therapy with either angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB). Computer-generated randomisation was done centrally using block sizes of four and six, and only the study statistician and the investigational pharmacy had the preset randomisation assignments. The primary outcome was change in left ventricular circumferential strain (Ecc) at 12 months, a measure of contractile dysfunction. Safety was established through serial serum potassium levels and measurement of cystatin C, a non-creatinine measure of kidney function. This trial is registered with ClinicalTrials.gov, number NCT01521546. FINDINGS Between Jan 26, 2012, and July 3, 2013, 188 boys were screened and 42 were enrolled. 20 were randomly assigned to receive eplerenone and 22 to receive placebo, of whom 20 in the eplerenone group and 20 in the placebo group completed baseline, 6-month, and 12-month visits. After 12 months, decline in left ventricular circumferential strain was less in those who received eplerenone than in those who received placebo (median ΔEcc 1·0 [IQR 0·3-2·2] vs 2·2 [1·3-3·1]; p=0·020). Cystatin C concentrations remained normal in both groups, and all non-haemolysed blood samples showed normal potassium concentrations. One 23-year-old patient in the placebo group died of fat embolism, and another patient in the placebo group withdrew from the trial to address long-standing digestive issues. All other adverse events were mild: short-lived headaches coincident with seasonal allergies occurred in one patient given eplerenone, flushing occurred in one patient given placebo, and anxiety occurred in another patient given placebo. INTERPRETATION In boys with Duchenne muscular dystrophy and preserved ejection fraction, addition of eplerenone to background ACEI or ARB therapy attenuates the progressive decline in left ventricular systolic function. Early use of available drugs warrants consideration in this population at high risk of cardiac death, but further studies are needed to determine the effect of combination cardioprotective therapy on event-free survival in Duchenne muscular dystrophy. FUNDING BallouSkies, Parent Project for Muscular Dystrophy, US National Center for Advancing Translational Sciences, and US National Institutes of Health.