Endocrine Aspects of Duchenne Muscular Dystrophy

Early Cardiac Dysfunction in Duchenne Muscular Dystrophy: A Case Report and Literature Update

Duchenne Muscular Dystrophy (DMD) is a severe X-linked recessive disorder characterized by progressive muscle degeneration due to dystrophin deficiency. Cardiac involvement, particularly dilated cardiomyopathy, significantly impacts morbidity and mortality, typically manifesting after age 10. This case report presents a rare instance of early-onset cardiac involvement in a 3-year-old male with a confirmed deletion in exon 55 of the dystrophin gene. The patient developed dilated cardiomyopathy at 3 years and 8 months, with progressive left ventricular dysfunction despite early treatment with corticosteroids, ACE inhibitors, and beta-blockers. Genetic mechanisms and genotype-phenotype correlations related to cardiac involvement were reviewed, highlighting emerging therapies such as exon skipping, vamorolone, ifetroban, and rimeporide. Studies indicate that variants in exons 12, 14-17, 31-42, 45, and 48-49 are associated with more severe cardiac impairment. This case emphasizes the need for early, ongoing cardiac assessment and personalized treatment to address disease heterogeneity. While current DMD care standards improve survival, optimizing management through early intervention and novel therapies remains essential. Further research is needed to better understand genotype-phenotype correlations and improve cardiac outcomes for patients with DMD.

A Parent Project Muscular Dystrophy-sponsored International Workshop Report on Endocrine and Bone Issues in Patients with Duchenne Muscular Dystrophy: An Ever-changing Landscape

In April 2023, over 30 experts and advocates from four countries met in Rome, Italy to discuss unmet needs in endocrine and bone health care for individuals with Duchenne muscular dystrophy (DMD). Despite recent advances in muscle-targeted therapy, long-term glucocorticoids (GC) remain the backbone of treatment for the foreseeable future. This affirms the need to intensify efforts that will mitigate serious complications of GC therapy, including unexpected mortality due to fat embolism syndrome following bone injury and also unrecognized adrenal suppression, early loss of ambulation linked to excess weight and/or fragility fracture, adverse cardiometabolic effects of GC, the psychosocial impact of profound growth and pubertal delay/hypogonadism, and the burden to families arising from monitoring and treating endocrine and skeletal complications of GC therapy. Delegates discussed: 1. The impact of GC therapy on the heart, 2. Predictors of fragility fractures and experience with intravenous and oral bisphosphonates plus teriparatide, 3. The effect of hormonal therapy on muscle-bone health, 4. Adrenal suppression, 5. Weight management, 6. Puberty, sexuality, fertility and gender identity, 7. The impact of early GC initiation, 8. Emerging knowledge about vamorolone (a novel dissociative steroid) and its effects on muscle, bone and endocrine health, and 9. Experiences implementing an endocrine-bone health management strategy nation-wide (in the UK). At the conclusion of the meeting, it was agreed that an endocrine-bone working group should be struck to continue the narrative, following which the International OPTIMIZE DMD Consortium was ignited to move the dial in these important areas.

The endocrine manifestations of adults with spinal muscular atrophy

INTRODUCTION/AIMS

Changes in body composition in patients with spinal muscular atrophy (SMA) can cause endocrine abnormalities that are insufficiently studied in adults. We aimed to assess the endocrine profile in a cohort of adults with SMA. Second, we compared body composition and endocrine profiles between nonambulatory and ambulatory patients and between different types of SMA.

METHODS

The cross-sectional study included 29 SMA patients (18 [62.1%] males and 11 [37.9%] females) of median age 44 (IQR 30-51.5) years with type 2, 3, or 4. Body composition was measured by bioimpedance. Morning blood samples were drawn for glycated hemoglobin (HbA1c), lipid profile, testosterone, cortisol, and insulin-like growth factor-1 (IGF-1). Blood glucose, insulin, and beta-hydroxybutyrate (BHB) were measured during a 75 g oral glucose tolerance test. The homeostatic model assessment for insulin resistance index was calculated.

RESULTS

In total, 75.9% of patients had increased fat mass (FM), with 51.7% having an increase despite normal body mass index. Ambulation was the most important discriminating factor of body composition. 93.1% of patients had metabolic abnormalities, including hyperglycemia, insulin resistance, and dyslipidemia. Increased BHB, a marker of ketosis, was present in more than a third of patients. Functional hypogonadism was present in half of male patients. Testosterone and IGF-1 negatively correlated with FM.

DISCUSSION

Adult patients with SMA had abnormal body composition and highly prevalent metabolic disturbances that might increase cardiometabolic risk. Because treatments have modified the course of SMA, it is important to investigate whether these observations translate into clinically relevant outcomes.

Choice of compound, dosage, and management of side effects for long-term corticosteroid treatment in Duchenne muscular dystrophy: Guidelines from the Neuromuscular Commission of the French Society of Pediatric Neurology

The French Society of Pediatric Neurology and the FILNEMUS network created a working group on corticosteroid therapy in children with Duchenne muscular dystrophy in order to analyze the literature review and current French practices. The aim of this work was to produce guidelines regarding treatment initiation, pre-therapeutic interventions, choice between available compounds, and treatment monitoring (dosage, duration, and discontinuation). The treatment side effects and their management are also detailed: osteoporosis, endocrinological anomaly (growth delay, weight gain, pubertal delay), cataract, arterial hypertension, behavioral disorders, management of immunosuppression and vaccines, and management of gastrointestinal and metabolic complications.

Is endocrine surveillance important in the care of Duchenne Muscular Dystrophy? Results from a national survey to patients and families on endocrine complications

Glucocorticoids are standard of care for patients with Duchenne muscular dystrophy (DMD). Although prolonged exposure is associated with multiple endocrine side effects, current guidelines related to monitoring and management of endocrinopathies are suboptimal. We aim to explore community perceptions of endocrine related complications in patients with DMD, assess current level of understanding, and desire for further education. A 31-item online survey was sent through Parent Project to Muscular Dystrophy (PPMD) to Duchenne Registry members to be completed by patients or their caretakers. Response rate was 55% (n = 75). Steroids were taken by 93%, but only 50% were followed by endocrinology and 21% report never been seen by endocrinology. Bone health was discussed with 87% of patients and 60% were diagnosed with osteoporosis. Delayed puberty was discussed with 41% of patients with 23% receiving testosterone therapy. About half the patients reported a diagnosis of slowed growth. Only 51% of the participants recalled discussing adrenal insufficiency. Obesity was discussed with 59% of participants. Families felt education about steroid-induced endocrinopathies to be very or extremely important and prefer to discuss about this at the beginning of their steroid therapy. This demonstrates significant gaps in education and access to endocrine care in patients with DMD.

Growth hormone therapy for children with Duchenne muscular dystrophy and glucocorticoid induced short stature

OBJECTIVE

To evaluate the outcome of recombinant human Growth Hormone (rhGH) therapy in patients with Duchene Muscular Dystrophy (DMD) and glucocorticoid treatment with compromised growth.

DESIGN

Four DMD patients on Deflzacort 0.6-0.85 mg/kg/day or prednisolone 0.625 mg/kg/day recieved rhGH (0.24 mg/kg/week) for 6-18 months. Primary outcomes were Growth velocity and Height for age Z-scores (Height SD).

RESULTS

Growth velocity increased from 0 to 3.25 cm/year prior to GH therapy to 3.3-7.8 cm/year over a period of 6-18 months. The typical Height SD decline in DMD was reversed in two patients and blunted in one. No adverse events or deterioration in cardiac or respiratory parameters were associated with the rhGH treatment.

CONCLUSIONS

rhGH appears to be safe and efficient in promoting growth of patients with glucocorticoid induced growth failure in DMD.

The Importance of Implementing a Transition Strategy for Patients with Muscular Dystrophy: From Child to Adult-Insights from a Tertiary Centre for Rare Neurological Diseases

Progress in the field of muscular dystrophy (MD) using a multidisciplinary approach based on international standards of care has led to a significant increase in the life expectancy of patients. The challenge of transitioning from pediatric to adult healthcare has been acknowledged for over a decade, yet it continues to be a last-minute concern. Currently, there is no established consensus on how to evaluate the effectiveness of the transition process. Our study aimed to identify how well patients are prepared for the transition and to determine their needs. We conducted a descriptive, cross-sectional study on 15 patients aged 14 to 21 years. The patients completed a sociodemographic and a Transition Readiness Assessment Questionnaire (TRAQ). We also analyzed the comorbidities of these patients. Our study revealed that only 46.7% of the patients had engaged in a conversation with a medical professional, namely, a child neurologist, about transitioning. A total of 60% of the participants expressed having confidence in their self-care ability. However, the median TRAQ score of 3.6 shows that these patients overestimate themselves. We emphasize the necessity for a slow, personalized transition led by a multidisciplinary team to ensure the continuity of state-of-the-art care from pediatric to adult healthcare services and the achievement of the highest possible quality of life for these patients.

Growth hormone secretagogues modulate inflammation and fibrosis in mdx mouse model of Duchenne muscular dystrophy

Introduction

Growth hormone secretagogues (GHSs) exert multiple actions, being able to activate GHS-receptor 1a, control inflammation and metabolism, to enhance GH/insulin-like growth factor-1 (IGF-1)-mediated myogenesis, and to inhibit angiotensin-converting enzyme. These mechanisms are of interest for potentially targeting multiple steps of pathogenic cascade in Duchenne muscular dystrophy (DMD).

Methods

Here, we aimed to provide preclinical evidence for potential benefits of GHSs in DMD, via a multidisciplinary in vivo and ex vivo comparison in mdx mice, of two ad hoc synthesized compounds (EP80317 and JMV2894), with a wide but different profile. 4-week-old mdx mice were treated for 8 weeks with EP80317 or JMV2894 (320 µg/kg/d, s.c.).

Results

In vivo, both GHSs increased mice forelimb force (recovery score, RS towards WT: 20% for EP80317 and 32% for JMV2894 at week 8). In parallel, GHSs also reduced diaphragm (DIA) and gastrocnemius (GC) ultrasound echodensity, a fibrosis-related parameter (RS: ranging between 26% and 75%). Ex vivo, both drugs ameliorated DIA isometric force and calcium-related indices (e.g., RS: 40% for tetanic force). Histological analysis highlighted a relevant reduction of fibrosis in GC and DIA muscles of treated mice, paralleled by a decrease in gene expression of TGF-β1 and Col1a1. Also, decreased levels of pro-inflammatory genes (IL-6, CD68), accompanied by an increment in Sirt-1, PGC-1α and MEF2c expression, were observed in response to treatments, suggesting an overall improvement of myofiber metabolism. No detectable transcript levels of GHS receptor-1a, nor an increase of circulating IGF-1 were found, suggesting the presence of a novel receptor-independent mechanism in skeletal muscle. Preliminary docking studies revealed a potential binding capability of JMV2894 on metalloproteases involved in extracellular matrix remodeling and cytokine production, such as ADAMTS-5 and MMP-9, overactivated in DMD.

Discussion

Our results support the interest of GHSs as modulators of pathology progression in mdx mice, disclosing a direct anti-fibrotic action that may prove beneficial to contrast pathological remodeling.

Humanization of the mdx Mouse Phenotype for Duchenne Muscular Dystrophy Modeling: A Metabolic Perspective

Duchenne muscular dystrophy (DMD) is a severe form of muscular dystrophy (MD) that is characterized by early muscle wasting and lethal cardiorespiratory failure. While the mdx mouse is the most common model of DMD, it fails to replicate the severe loss of muscle mass and other complications observed in patients, in part due to the multiple rescue pathways found in mice. This led to several attempts at improving DMD animal models by interfering with these rescue pathways through double transgenic approaches, resulting in more severe phenotypes with mixed relevance to the human pathology. As a growing body of literature depicts DMD as a multi-system metabolic disease, improvements in mdx-based modeling of DMD may be achieved by modulating whole-body metabolism instead of muscle homeostasis. This review provides an overview of the established dual-transgenic approaches that exacerbate the mild mdx phenotype by primarily interfering with muscle homeostasis and highlights how advances in DMD modeling coincide with inducing whole-body metabolic changes. We focus on the DBA2/J strain-based D2.mdx mouse with heightened transforming growth factor (TGF)-β signaling and the dyslipidemic mdx/apolipoprotein E (mdx/ApoE) knock-out (KO) mouse, and summarize how these novel models emulate the metabolic changes observed in DMD.

The Relation Between Nutritional Intake and Weight in 4–18 Year Old Patients with DMD: What could possibly be done to prevent weight gain?

Background: Overweight is a common problem in Duchenne muscular dystrophy (DMD) and is associated with reduced mobility and quality of life. The influence of nutritional intake on (over)weight is unclear. Objective: To investigate weight and energy and macronutrients intake compared to age-specific requirements in DMD patients (4–18 years). Methods: We assessed weight and body mass index (BMI) and the amount of energy (kcal/day) and macronutrients based on self-reported nutrition diaries. Nutritional intake was compared to requirements for 3 age-groups according to the Dutch Healthy Diet Guideline (4–8/9–13/14–18 years) using a student’s t-test, and relations with age and BMI were investigated by means of Pearson’s correlations. Results: Forty-eight patients participated, 22 ambulatory, median age 10.8 years. The majority used corticosteroids (N = 41). Overweight (BMI z-score >  2.07) was present in 19 patients; 6% (4–8 years), 73% (9–13 years) and 47% (14–18 years). Overweight was more common in non-ambulatory (61.6%) than ambulatory patients (13.6%). Patients aged 4–8 received 290 kcal/day more than required (p <  0.001). Patients aged 9–13 received 349 kcal/day (p = 0.005) less than required. Overall, intake of fibre, nuts, meat/fish/eggs/legumes and dairy was lower than recommended (p <  0.05). The difference between energy intake versus requirement correlated moderately to age (r = –0.549, p <  0.001) and BMI (r = –0.562, p <  0.001). Conclusions: Overweight was found especially in patients aged 9–18 even though they received less energy than required. Younger patients (4–8) had good weight but consumed more energy than required. All patients did not consume enough fibre, nuts, meat/fish/eggs/legumes and dairy. Limiting energy and increasing fibre/protein intake at an early age may prevent overweight at a later age.

A single-centre study on predictors and determinants of pubertal delay and growth impairment in Epidermolysis Bullosa

Background

Delayed puberty is a possible complication of Epidermolysis Bullosa (EB), though the actual incidence is still unknown. In chronic illnesses delayed puberty should be correctly managed since, if untreated, can have detrimental effects on adult height attainment, peak bone mass achievement and psychological health.

Aims and methods

This is a single-centre study on pubertal development, growth and bone status in EB. Auxological, densitometric (areal Bone Mineral Density-aBMD Z-score, Bone Mineral Apparent Density-BMAD Z-score, Trabecular Bone Score-TBS and Bone Strain Index-BSI at Lumbar spine) and body composition data (Total Body DXA scans) were collected. Disease severity was defined according to Birmingham Epidermolysis Bullosa Severity (BEBS) score.

Results

Twenty-one patients (12 Recessive Dystrophic EB-RDEB, 3 Dominant Dystrophic EB, 3 Junctional EB-JEB, 2 EB Simplex and one Kindler EB) aged 13 years (females) or 14 years (males) and above were enrolled (age 16.2±2.5 years, M/F 11/10). Short stature was highly prevalent (57%, mean height -2.12±2.05 SDS) with 55% patients with height <-2SD their mid-parental height. 7/21 patients (33%, 6 RDEB and 1 JEB) had delayed puberty with a median BEBS of 50 (range 29 to 63), a height SDS of -2.59 SDS (range -5.95 to -2.22) and a median lumbar BMAD Z-score of -4.0 SDS (range -5.42 to -0.63 SDS). Pubertal status was negatively associated with BEBS, skin involvement, inflammatory state and positively with height SDS and BMI SDS.

Conclusions

Pubertal delay is highly prevalent in EB, especially in patients with RDEB and JEB, high severity score and inflammatory state. Moreover, pubertal delay worsens growth impairment and bone health. A study on pubertal induction is ongoing to enlighten possible beneficial effects on adult height attainment and peak bone mass accrual.

Emergency Planning as Part of Healthcare Transition Preparation for Patients with Duchenne Muscular Dystrophy

BACKGROUND

Emergency care planning is an important component of healthcare transition, particularly for patients with medical complexity. Duchenne muscular dystrophy (DMD) is a complex, progressive pediatric-onset disease affecting multiple organ systems including impairment of cardiac and pulmonary function, high risk for fractures, fat embolism, adrenal crisis and malignant hyperthermia. Appropriate interdisciplinary emergency management is critical for survival for these patients. The purpose of this quality improvement project was to develop a process to reliably share an individualized emergency care plan (ECP) with patients and their families as part of a larger plan to develop an integrated transition program.

METHODS

An interdisciplinary team of nurses and clinicians used the principles of quality improvement to develop a reliable process to assure patients with DMD received an individualized, multidisciplinary ECP at routine interdisciplinary clinic visits. Additionally, the project used surveys to assess patient and family satisfaction with the letter and whether it improved their knowledge of emergency care.

RESULTS

Sixty-two patients were seen during the study timeframe. All received an ECP. Sixty-two surveys were sent and twenty-three surveys were returned. Of those that responded, the majority stated the ECP increased their knowledge of emergency care.

CONCLUSION

ECPs can be developed and disseminated to patients with DMD and their caregivers. This tool can potentially promote timely and appropriate emergency care for these patients with unique and complex medical needs.

The effect of oral bisphosphonate therapy on vertebral morphometry and fractures in patients with Duchenne muscular dystrophy and glucocorticoid-induced osteoporosis

INTRODUCTION/AIMS

Glucocorticoid-induced osteoporosis with vertebral fractures is frequent in patients with Duchenne muscular dystrophy (DMD). In this study, we evaluated the effects of oral bisphosphonate (BP) therapy on the prevalence and severity of vertebral fractures by vertebral morphometry assessment.

METHODS

We reviewed the records and radiographs of patients with DMD who had been treated with oral BP (weekly alendronate) and had undergone routine spine radiographic monitoring for glucocorticoid-induced osteoporosis at Cincinnati Children's Hospital Medical Center between 2010 and 2017. Study outcomes were thoracic and lumbar vertebral fracture prevalence and severity, assessed by Genant semiquantitative grading of vertebral morphometry, for up to 5 years of treatment.

RESULTS

Fifty-two patients (median age, 11.8 years; 88% prepubertal; 31% nonambulatory) had been treated with long-term glucocorticoids (median duration, 4.7 years at BP start). Most patients (75%) had mild vertebral height loss or fractures (Genant grade = 0 or 1) at baseline. The prevalence of vertebral fractures at each year of treatment was not statistically different from that at baseline (P = .08-1.00). Serial radiographs showed no longitudinal change in severity by Genant grade in most vertebrae (64%-80%). Improvement in vertebral fracture grade was observed in some patients.

DISCUSSION

We observed stable prevalence of vertebral fractures and no change in severity by Genant grade in most vertebrae for up to 5 years of treatment. Oral BP may mitigate development or progression of vertebral fractures and be beneficial for secondary prevention of glucocorticoid-induced osteoporosis in this population.

Pathogenesis of Musculoskeletal Deficits in Children and Adults with Inflammatory Bowel Disease

Musculoskeletal deficits are among the most commonly reported extra-intestinal manifestations and complications of inflammatory bowel disease (IBD), especially in those with Crohn’s disease. The adverse effects of IBD on bone and muscle are multifactorial, including the direct effects of underlying inflammatory disease processes, nutritional deficits, and therapeutic effects. These factors also indirectly impact bone and muscle by interfering with regulatory pathways. Resultantly, individuals with IBD are at increased risk of osteoporosis and sarcopenia and associated musculoskeletal morbidity. In paediatric IBD, these factors may contribute to suboptimal bone and muscle accrual. This review evaluates the main pathogenic factors associated with musculoskeletal deficits in children and adults with IBD and summarises the current literature and understanding of the musculoskeletal phenotype in these patients.

Bone density and bone health alteration in boys with Duchenne Muscular Dystrophy: a prospective observational study

OBJECTIVES

Boys with Duchenne Muscular Dystrophy (DMD) are at increased risk for compromised bone health, manifesting as low-impact trauma long bone fractures and vertebral compression fractures.

METHODS

In a prospective observational study, we studied bone health parameters in North Indian boys with DMD. We consecutively enrolled ambulatory boys with DMD on glucocorticoid therapy. Bone health was evaluated with X-ray spine, Dual-energy X-ray absorptiometry (DXA), serum calcium, vitamin D3 (25[OH]D), 1,25-dihyroxyvitamin D3 (1,25[OH]₂D₃), serum osteocalcin, osteopontin, and N terminal telopeptide of type 1 collagen (Ntx) levels.

RESULTS

A total of 76 boys with DMD were enrolled. The median age was 8.5 (interquartile range [IQR] 7.04-10.77) years. Among these, seven (9.2%) boys had long bone fractures, and four (5.3%) had vertebral compression fractures. Fifty-four (71%) boys underwent DXA scan, and among these 31 (57%) had low bone mineral density (BMD, ≤-2 z-score) at the lumbar spine. The mean BMD z-score at the lumbar spine was -2.3 (95% confidence interval [CI] = -1.8, -2.8), and at the femoral neck was -2.5 (95% CI = -2, -2.9). 25(OH)D levels were deficient in 68 (89.5%, n=76) boys, and 1,25(OH)₂D₃ levels were deficient in all. Mean serum osteocalcin levels were 0.68 ± 0.38 ng/mL (n=54), serum osteopontin levels were 8.6 ± 4.6 pg/mL (n=54) and serum Ntx levels were 891 ± 476 nmol/L (n=54). Boys with low BMD received glucocorticoids for longer duration, in comparison to those with normal BMD (median, IQR [16.9 (6-34) months vs. 7.8 (4.8-13.4) months]; p=0.04).

CONCLUSIONS

Bone health is compromised in North Indian boys with DMD. BMD at the lumbar spine is reduced in more than half of boys with DMD and nearly all had vitamin D deficiency on regular vitamin D supplements. Longer duration of glucocorticoid therapy is a risk factor for low BMD in our cohort.

Age-related changes in appendicular lean mass in males with Duchenne muscular dystrophy: A retrospective review

BACKGROUND

Appendicular lean mass (ALM) trajectory in males with Duchenne muscular dystrophy (DMD) has potential applicability for treatment and research and has not been characterized.

METHODS

This chart review included longitudinal data on 499 males with DMD receiving glucocorticoids and 693 controls, ages 5 to 22.9 y. ALM (kg) was measured by dual energy x-ray absorptiometry (DXA). Appendicular lean mass index (ALMI, kg/m² ) was calculated for height adjustment. Reference centiles were generated using data from healthy controls, and ALM and ALMI Z-scores were calculated for patients with DMD. Generalized linear models were used to estimate median Z-scores by age and functional mobility status (FMS) score. ALM velocity by age was modeled using superimposition, translation and rotation (SITAR).

RESULTS

Compared to controls, males with DMD had lower ALM from an early age. ALMI Z-scores dropped below 0 at age 8 y or FMS of 2, and below -2.0 at age 13 y or FMS of 3 (P < .05). Age at peak ALM velocity was similar in both groups, but the magnitude was higher in controls (3.5 vs. 0.7 kg/y, P < .0001). Patients with DMD had a transient loss of ALM around age 12 y, an increase at age 14 y, then a further decline at age 16 y, remaining low thereafter.

CONCLUSIONS

Males with DMD have progressive decline in lean mass with age and worsening functional mobility. DXA measurement of ALM may be useful for monitoring lean mass status in patients with DMD, providing valuable information for individual treatment plans and research endeavors.

Safety and efficacy of teriparatide treatment for severe osteoporosis in patients with Duchenne muscular dystrophy

Osteoporosis is a major concern in patients with Duchenne muscular dystrophy. In this novel study of teriparatide treatment in 6 patients with severe osteoporosis, bone health (fractures, vertebral morphometry, and DXA) remained stable, with no adverse events. These findings will help inform future osteoporosis research in this challenging population.

INTRODUCTION

Despite standard therapy with vitamin D and bisphosphonates (BP), many patients with Duchenne muscular dystrophy (DMD) continue to sustain fragility fractures due to long-term glucocorticoid treatment and limited mobility. We aimed to evaluate the safety and efficacy of teriparatide for the treatment of severe osteoporosis in adolescent and young adult patients with DMD.

METHODS

We prospectively treated 6 patients with DMD who had severe osteoporosis with teriparatide 20 mcg subcutaneously daily for 1-2 years. Inclusion criteria were long-term glucocorticoid therapy, and severe osteoporosis despite treatment with BP, or intolerance to BP. We examined long bone and vertebral fracture outcomes, including vertebral morphometry measures, bone mineral density and content, bone formation markers, safety indices, and adverse events.

RESULTS

The mean age at teriparatide start was 17.9 years (range 13.9-22.1 years). All 6 patients were on daily glucocorticoids (mean ± SD; duration 10.9 ± 2.5 years) and 5 were non-ambulatory. Five patients had been treated with BP for 7.9 ± 4.2 years. All had vertebral and a history of long bone fragility fractures at baseline. Vertebral heights and Genant fracture grading remained stable. Long bone fracture rate appeared to decrease (from 0.84/year to 0.09/year); one patient sustained a long bone fracture at 6 months of treatment. Trajectories for change in bone mineral density and content were not different post- vs. pre-teriparatide. Procollagen type 1 amino-terminal propeptide (P1NP) increased, while laboratory safety indices remained stable and non-concerning. No adverse events were observed.

CONCLUSION

In six patients with DMD treated with teriparatide for severe osteoporosis, we observed stable bone health and modest increases in P1NP, without safety concerns. Further studies are needed to better understand teriparatide efficacy for treatment of osteoporosis in patients with DMD.

Tandem Mass Tag-Based Serum Proteome Profiling for Biomarker Discovery in Young Duchenne Muscular Dystrophy Boys

Blood-accessible molecular biomarkers are becoming highly attractive tools to assess disease progression and response to therapies in Duchenne muscular dystrophy (DMD) especially in very young patients for whom other outcome measures remain subjective and challenging. In this study, we have standardized a highly specific and reproducible multiplexing mass spectrometry method using the tandem mass tag (TMT) strategy in combination with depletion of abundant proteins from serum and high-pH reversed-phase peptide fractionation. Differential proteome profiling of 4 year-old DMD boys (n = 9) and age-matched healthy controls (n = 9) identified 38 elevated and 50 decreased serum proteins (adjusted P < 0.05, FDR <0.05) in the DMD group relative to the healthy control group. As expected, we confirmed previously reported biomarkers but also identified novel biomarkers. These included novel muscle injury-associated biomarkers such as telethonin, smoothelin-like protein 1, cofilin-1, and plectin, additional muscle-specific enzymes such as UTP-glucose-1-phosphate uridylyltransferase, aspartate aminotransferase, pyruvate kinase PKM, lactotransferrin, tissue alpha-l-fucosidase, pantetheinase, and ficolin-1, and some pro-inflammatory and cell adhesion-associated biomarkers such as leukosialin, macrophage receptor MARCO, vitronectin, galectin-3-binding protein, and ProSAAS. The workflow including serum depletion, sample processing, and mass spectrometry analysis was found to be reproducible and stable over time with CV < 20%. Furthermore, the method was found to be superior in terms of specificity compared to other multiplexing affinity-based methods. These findings demonstrate the specificity and reliability of TMT-based mass spectrometry methods in detection and identification of serum biomarkers in presymptomatic young DMD patients.

Recombinant human insulin-like growth factor-1 therapy for 6 months improves growth but not motor function in boys with Duchenne muscular dystrophy

INTRODUCTION

Recombinant human insulin-like growth factor-1 (rhIGF-1) is a growth factor and has anabolic effects on muscle. We investigated whether rhIGF-1 therapy: 1) improves or preserves muscle function; and 2) improves growth in boys with Duchenne muscular dystrophy (DMD).

METHODS

In this study we compared prepubescent, ambulatory, glucocorticoid-treated boys with DMD (n = 17) vs controls (glucocorticoid therapy only, n = 21) in a 6-month-long, prospective, randomized, controlled trial of subcutaneous rhIGF-1 therapy. The primary outcome was 6-minute walk distance (6MWD). Secondary outcomes included height velocity (HV), change in height standard deviation score (ΔHtSDS), motor function, cardiopulmonary function, body composition, insulin sensitivity, quality of life, and safety.

RESULTS

Change in 6MWD was similar between groups (rhIGF-1 vs controls [mean ± SD]: 3.4 ± 32.4 vs -5.1 ± 50.2 meters, P = .53). Treated subjects grew more than controls (HV: 6.5 ± 1.7 vs 3.3 ± 1.3 cm/year, P < .0001; 6-month ΔHtSDS: 0.25, P < .0001). Lean mass and insulin sensitivity increased in treated subjects.

DISCUSSION

In boys with DMD, 6 months of rhIGF-1 therapy did not change motor function, but it improved linear growth.

Cultured hippocampal neurons of dystrophic mdx mice respond differently from those of wild type mice to an acute treatment with corticosterone

Duchenne muscular dystrophy is a lethal genetic disease characterised by progressive degeneration of skeletal muscles induced by deficiency of dystrophin, a cytoskeletal protein expressed in myocytes and in certain neuron populations. The severity of the neurological disorder varies in humans and animal models owing to dysfunction in numerous brain areas, including the hippocampus. Cyclic treatments with high-dose glucocorticoids remain a major pharmacological approach for treating the disease; however, elevated systemic levels of either stress-induced or exogenously administered anti-inflammatory molecules dramatically affect hippocampal activity. In this study, we analysed and compared the response of hippocampal neurons isolated from wild-type and dystrophic mdx mice to acute administration of corticosterone in vitro, without the influence of other glucocorticoid-regulated processes. Our results showed that in neurons of mdx mice, both the genomic and intracellular signalling-mediated responses to corticosterone were affected compared to those in wild-type animals, evoking the characteristic response to detrimental chronic glucocorticoid exposure. Responsiveness to glucocorticoids is, therefore, another function of hippocampal neurons possibly affected by deficiency of Dp427 since embryonic development. Knowing the pivotal role of hippocampus in stress hormone signalling, attention should be paid to the effects that prolonged glucocorticoid treatments may have on this and other brain areas of DMD patients.

The role of delayed bone age in the evaluation of stature and bone health in glucocorticoid treated patients with Duchenne muscular dystrophy

Background

Low bone mineral density and an increased risk of appendicular and vertebral fractures are well-established consequences of Duchenne muscular dystrophy (DMD) and the risk of fractures is exacerbated by long-term glucocorticoid treatment. Monitoring of endocrine and skeletal health and timely intervention in at-risk patients is important in the management of children with DMD.

Methods

As part of the Norwegian Duchenne muscular dystrophy cohort study, we examined the skeletal maturation of 62 boys less than 18 years old, both currently glucocorticoid treated (n = 44), previously treated (n = 6) and naïve (n = 12). The relationship between bone age, height and bone mineral density (BMD) Z-scores was explored.

Results

The participants in the glucocorticoid treated group were short in stature and puberty was delayed. Bone age was significantly delayed, and the delay increased with age and duration of treatment. The difference in height between glucocorticoid treated and naïve boys was no longer significant when height was corrected for delayed skeletal maturation. Mean BMD Z-scores fell below − 2 before 12 years of age in the glucocorticoid treated group, with scores significantly correlated with age, duration of treatment and pubertal development. When BMD Z-scores were corrected for by retarded bone age, the increase in BMD Z-scores was significant for all age groups.

Conclusion

Our results suggest that skeletal maturation should be assessed in the evaluation of short stature and bone health in GC treated boys with DMD, as failing to consider delayed bone age leads to underestimation of BMD Z-scores and potentially overestimation of fracture risk.

Neuromuscular Diseases and Bone

Neuromuscular diseases (NMDs) are inherited or acquired conditions affecting skeletal muscles, motor nerves, or neuromuscular junctions. Most of them are characterized by a progressive damage of muscle fibers with reduced muscle strength, disability, and poor health-related quality of life of affected patients. In this scenario, skeletal health is usually compromised as a consequence of modified bone-muscle cross-talk including biomechanical and bio-humoral issues, resulting in increased risk of bone fragility and fractures. In addition, NMD patients frequently face nutritional issues, including malnutrition due to feeding disorders and swallowing problems that might affect bone health. Moreover, in these patients, low levels of physical activity or immobility are common and might lead to overweight or obesity that can also interfere with bone strength features. Also, vitamin D deficiency could play a critical role both in the pathogenesis and in the clinical scenario of many NMDs, suggesting that its correction could be useful in maintaining or enhancing bone health, especially in the early phases of NMDs. Last but not least, specific disease-modifying drugs, available for some NMDs, are frequently burdened with adverse effects on bone tissue. For example, glucocorticoid therapy, standard of care for many muscular dystrophies, prolongs long-term survival in treated patients; nevertheless, high dose and/or chronic use of these drugs are a common cause of secondary osteoporosis. This review addresses the current state of knowledge about the factors that play a role in determining bone alterations reported in NMDs, how these factors can modify the biological pathways underlying bone health, and which are the available interventions to manage bone involvement in patients affected by NMDs. Considering the complexity of care of these patients, an interdisciplinary and multimodal management strategy based on both pharmacological and non-pharmacological interventions is recommended, particularly targeting musculoskeletal issues that are closely related to functional independence as well as social implications.

Growth, pubertal development, and skeletal health in boys with Duchenne Muscular Dystrophy

PURPOSE OF REVIEW

Glucocorticoid therapy is currently the most widely used treatment for Duchenne muscular dystrophy (DMD), having consistently shown to prolong ambulation by 2 years, reduce the frequency of scoliosis, and improve cardiorespiratory function. Among the most frequent side effects of glucocorticoids are fractures due to osteoporosis, linear growth retardation or arrest, and pubertal delay, the subjects of this review.

RECENT FINDINGS

The diagnosis of osteoporosis has shifted in recent years away from a bone mineral density-centric to a fracture-focused approach, with particular emphasis on early vertebral fracture identification (one of the key triggers for osteoporosis intervention). Delayed puberty should be addressed in an age-appropriate manner, with numerous options available for sex steroid replacement. Growth impairment, however, is a more challenging complication of glucocorticoid-treated DMD, one that is most likely best addressed through growth-sparing therapies that target the dystrophinopathy.

SUMMARY

With glucocorticoid prescription an increasingly prevalent component of DMD care, early attention to management of osteoporosis and delayed puberty are important components of multidisciplinary and anticipatory care. The treatment of short stature remains controversial, with no accepted therapy currently available to over-ride the toxic effects of glucocorticoids on the growth axis.

Body composition and body mass index in Duchenne muscular dystrophy: Role of dietary intake

INTRODUCTION

In Duchenne muscular dystrophy (DMD) muscle is replaced by adipose tissue. The role of dietary intake (DI) in DMD has not been evaluated. In this study we examined body composition, body mass index (BMI), and adequacy of DI in patients with DMD and evaluated the influence of DI on body composition.

METHODS

Patients (n = 101; age 3-18 years; BMI 11.8-29.5 kg/m² ) completed a dietary recall to determine DI and then underwent dual-energy X-ray absorptiometry to determine body composition.

RESULTS

Preschool-age and school-age boys with DMD had high total energy intake. Protein intake per kilogram exceeded recommendations. As age increased, the percentage of boys with abnormal BMI and fat mass increased, while lean mass decreased. Dietary intake did not predict body fat or lean mass.

DISCUSSION

Age-dependent changes in BD in boys with DMD may be due to endogenous metabolic factors related to the underlying disease process and to disease-related mobility impairments. Muscle Nerve 59:295-302, 2019.

Vertebral Fractures in Duchenne Muscular Dystrophy Patients Managed With Deflazacort

BACKGROUND

Corticosteroids are widely used in the management of patients with Duchenne muscular dystrophy (DMD). They improve quality of life in these patients by prolonging ambulation and preserving cardiorespiratory status. However, corticosteroid treatment is associated with a decrease in bone mineral density (BMD) and an increased risk of vertebral fractures (VF). The purpose of this study was to investigate the prevalence of VF in patients with DMD undergoing long-term treatment with the corticosteroid deflazacort.

METHODS

We retrospectively reviewed 49 male patients with DMD on long-term deflazacort therapy at a single institution. All patients had received deflazacort for at least 2 years. VF prevalence, age at start of deflazacort treatment, duration of treatment, BMD Z-score and patient ambulatory status at the time of fracture were evaluated.

RESULTS

Of the 49 patients on long-term deflazacort treatment, 26 had VF. Out of these patients who had VF, 19% showed evidence of VF in their third year of therapy, 50% within 5 years of starting therapy, 69% within 7 years of starting therapy, and 100% within 9 years. The first evidence of VF was observed at mean BMD Z-score, lumbar (L)=-2.2 and whole body (B)=-3.1. Eighty-five percent of these patients had at least 3 collapsed vertebrae. Mean BMD Z-score at the time of or before when multiple fractures were noted was -2.4 (L) and -3.4 (B). Patients who started deflazacort at age 3 to 5, 5 to 7 or 7 to 9 years developed a VF after a mean of 4.7, 5.4, or 5.7 years, respectively. Sixty-two percent of patients had VF by the age of 12 years and 91% of patients by age of 15 years. Twenty-one of 26 patients were ambulatory at the time of VF.

CONCLUSIONS

Our findings suggest that there is a high risk of VF associated with length of deflazacort use in DMD patients, regardless of age at start of therapy.

LEVEL OF EVIDENCE

Level III-retrospective therapeutic study.

Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and neuromuscular, rehabilitation, endocrine, and gastrointestinal and nutritional management

Since the publication of the Duchenne muscular dystrophy (DMD) care considerations in 2010, multidisciplinary care of this severe, progressive neuromuscular disease has evolved. In conjunction with improved patient survival, a shift to more anticipatory diagnostic and therapeutic strategies has occurred, with a renewed focus on patient quality of life. In 2014, a steering committee of experts from a wide range of disciplines was established to update the 2010 DMD care considerations, with the goal of improving patient care. The new care considerations aim to address the needs of patients with prolonged survival, to provide guidance on advances in assessments and interventions, and to consider the implications of emerging genetic and molecular therapies for DMD. The committee identified 11 topics to be included in the update, eight of which were addressed in the original care considerations. The three new topics are primary care and emergency management, endocrine management, and transitions of care across the lifespan. In part 1 of this three-part update, we present care considerations for diagnosis of DMD and neuromuscular, rehabilitation, endocrine (growth, puberty, and adrenal insufficiency), and gastrointestinal (including nutrition and dysphagia) management.

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

BACKGROUND

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.

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

Nutritional Challenges in Duchenne Muscular Dystrophy

Neuromuscular diseases (NMDs) represent a heterogeneous group of acquired or inherited conditions. Nutritional complications are frequent in NMDs, but they are sometimes underestimated. With the prolongation of survival in patients with NMDs, there are several nutritional aspects that are important to consider, including the deleterious effects of overnutrition on glucose metabolism, mobility, and respiratory and cardiologic functions; the impact of hyponutrition on muscle and ventilatory function; constipation and other gastrointestinal complications; chewing/swallowing difficulties with an increased risk of aspiration that predisposes to infectious diseases and respiratory complications; as well as osteoporosis with an associated increased risk of fractures. The aim of this review is to provide a comprehensive analysis of the nutritional aspects and complications that can start in children with Duchenne muscular dystrophy (DMD) and increase with ageing. These aspects should be considered in the transition from paediatric clinics to adult services. It is shown that appropriate nutritional care can help to improve the quality of life of DMD patients, and a multidisciplinary team is needed to support nutrition challenges in DMD patients. However, studies on the prevalence of overnutrition and undernutrition, gastrointestinal complications, infectious diseases, dysphagia, and reduced bone mass in the different types of NMDs are needed, and appropriate percentiles of weight, height, body mass index, and body composition appear to be extremely important to improve the management of patients with NMD.

Long-Term Outcome of Interdisciplinary Management of Patients with Duchenne Muscular Dystrophy Receiving Daily Glucocorticoid Treatment

OBJECTIVE

To evaluate clinical outcomes and steroid side effects in a cohort of patients with Duchenne muscular dystrophy (DMD) treated with long-term daily glucocorticoid therapy. Although daily glucocorticoid therapy has been shown to extend ambulatory function in DMD, less frequent dosing is often used because of side effect concerns.

STUDY DESIGN

Retrospective study of 97 patients with DMD aged 10 to <16 years treated with daily glucocorticoid (89% on deflazacort) for a mean of 8.5 years. Outcome measures were motor, pulmonary, and cardiac function, and scoliosis. Side effects were growth failure and weight gain, facial fullness, blood pressure, bone health, cataracts, gastrointestinal symptoms, behavior, hypertrichosis, and need for medication interventions.

RESULTS

For 13- to 16-year-old patients, 40% could rise from the floor and 50% could perform the 30-foot run test. Forced vital capacity for the entire cohort was well preserved. Thirteen percent of younger (10- to <13-year-old) and 21% of older patients had findings of left ventricle systolic dysfunction. Six percent (all aged 16 years) developed scoliosis (Cobb angle >20 degrees). Eighty-six percent had normal weight velocities; 30% had no increased facial fullness; 72% had short stature; and 19% had asymptomatic cataracts. Asymptomatic spine compression deformities were noted in 76% and long bone fractures in 30%. One patient stopped glucocorticoid because of behavioral concerns.

CONCLUSIONS

With evidence for improved outcomes and manageable side effects, we recommend use of daily glucocorticoid therapy for patients with DMD with anticipatory management of side effects and a coordinated interdisciplinary care approach.

Interventions to prevent and treat corticosteroid-induced osteoporosis and prevent osteoporotic fractures in Duchenne muscular dystrophy

BACKGROUND

Corticosteroid treatment is considered the 'gold standard' for Duchenne muscular dystrophy (DMD); however, it is also known to induce osteoporosis and thus increase the risk of vertebral fragility fractures. Good practice in the care of those with DMD requires prevention of these adverse effects. Treatments to increase bone mineral density include bisphosphonates and vitamin D and calcium supplements, and in adolescents with pubertal delay, testosterone. Bone health management is an important part of lifelong care for patients with DMD.

OBJECTIVES

To assess the effects of interventions to prevent or treat osteoporosis in children and adults with DMD taking long-term corticosteroids; to assess the effects of these interventions on the frequency of vertebral fragility fractures and long-bone fractures, and on quality of life; and to assess adverse events.

SEARCH METHODS

On 12 September 2016, we searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL Plus to identify potentially eligible trials. We also searched the Web of Science ISI Proceedings (2001 to September 2016) and three clinical trials registries to identify unpublished studies and ongoing trials. We contacted correspondence authors of the included studies in the review to obtain information on unpublished studies or work in progress.

SELECTION CRITERIA

We considered for inclusion in the review randomised controlled trials (RCTs) and quasi-RCTs involving any bone health intervention for corticosteroid-induced osteoporosis and fragility fractures in children, adolescents, and adults with a confirmed diagnosis of DMD. The interventions might have included oral and intravenous bisphosphonates, vitamin D supplements, calcium supplements, dietary calcium, testosterone, and weight-bearing activity.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed reports and selected potential studies for inclusion, following standard Cochrane methodology. We contacted study authors to obtain further information for clarification on published work, unpublished studies, and work in progress.

MAIN RESULTS

We identified 18 potential studies, of which two, currently reported only as abstracts, met the inclusion criteria for this review. Too little information was available for us to present full results or adequately assess risk of bias. The participants were children aged five to 15 years with DMD, ambulant and non-ambulant. The interventions were risedronate versus no treatment in one trial (13 participants) and whole-body vibration versus a placebo device in the second (21 participants). Both studies reported improved bone mineral density with the active treatments, with no improvement in the control groups, but the abstracts did not compare treatment and control conditions. All children tolerated whole-body vibration treatment. No study provided information on adverse events. Two studies are ongoing: one investigating whole-body vibration, the other investigating zoledronic acid.

AUTHORS' CONCLUSIONS

We know of no high-quality evidence from RCTs to guide use of treatments to prevent or treat corticosteroid-induced osteoporosis and reduce the risk of fragility fractures in children and adults with DMD; only limited results from two trials reported in abstracts were available. We await formal trial reports. Findings from two ongoing relevant studies and two trials, for which only abstracts are available, will be important in future updates of this review.

Nutraceuticals and Their Potential to Treat Duchenne Muscular Dystrophy: Separating the Credible from the Conjecture

In recent years, complementary and alternative medicine has become increasingly popular. This trend has not escaped the Duchenne Muscular Dystrophy community with one study showing that 80% of caregivers have provided their Duchenne patients with complementary and alternative medicine in conjunction with their traditional treatments. These statistics are concerning given that many supplements are taken based on purely "anecdotal" evidence. Many nutraceuticals are thought to have anti-inflammatory or anti-oxidant effects. Given that dystrophic pathology is exacerbated by inflammation and oxidative stress these nutraceuticals could have some therapeutic benefit for Duchenne Muscular Dystrophy (DMD). This review gathers and evaluates the peer-reviewed scientific studies that have used nutraceuticals in clinical or pre-clinical trials for DMD and thus separates the credible from the conjecture.

Validation of ultrasonography for non-invasive assessment of diaphragm function in muscular dystrophy

KEY POINTS

Duchenne muscular dystrophy (DMD) is a severe, degenerative muscle disease that is commonly studied using the mdx mouse. The mdx diaphragm muscle closely mimics the pathophysiological changes in DMD muscles. mdx diaphragm force is commonly assessed ex vivo, precluding time course studies. Here we used ultrasonography to evaluate time-dependent changes in diaphragm function in vivo, by measuring diaphragm movement amplitude. In mdx mice, diaphragm amplitude decreased with age and values were much lower than for wild-type mice. Importantly, diaphragm amplitude strongly correlated with ex vivo specific force values. Micro-dystrophin administration increased mdx diaphragm amplitude by 26% after 4 weeks. Diaphragm amplitude correlated positively with ex vivo force values and negatively with diaphragm fibrosis, a major cause of DMD muscle weakness. These studies validate diaphragm ultrasonography as a reliable technique for assessing time-dependent changes in mdx diaphragm function in vivo. This technique will be valuable for testing potential therapies for DMD.

ABSTRACT

Duchenne muscular dystrophy (DMD) is a severe, degenerative muscle disease caused by dystrophin mutations. The mdx mouse is a widely used animal model of DMD. The mdx diaphragm muscle most closely recapitulates key features of DMD muscles, including progressive fibrosis and considerable force loss. Diaphragm function in mdx mice is commonly evaluated by specific force measurements ex vivo. While useful, this method only measures force from a small muscle sample at one time point. Therefore, accurate assessment of diaphragm function in vivo would provide an important advance to study the time course of functional decline and treatment benefits. Here, we evaluated an ultrasonography technique for measuring time-dependent changes of diaphragm function in mdx mice. Diaphragm movement amplitude values for mdx mice were considerably lower than those for wild-type, decreased from 8 to 18 months of age, and correlated strongly with ex vivo specific force. We then investigated the time course of diaphragm amplitude changes following administration of an adeno-associated viral vector expressing Flag-micro-dystrophin (AAV-μDys) to young adult mdx mice. Diaphragm amplitude peaked 4 weeks after AAV-μDys administration, and was 26% greater than control mdx mice at this time. This value decreased slightly to 21% above mdx controls after 12 weeks of treatment. Importantly, diaphragm amplitude again correlated strongly with ex vivo specific force. Also, diaphragm amplitude and specific force negatively correlated with fibrosis levels in the muscle. Together, our results validate diaphragm ultrasonography as a reliable technique for assessing time-dependent changes in dystrophic diaphragm function in vivo, and for evaluating potential therapies for DMD.

Vitamin D in corticosteroid-naïve and corticosteroid-treated Duchenne muscular dystrophy: what dose achieves optimal 25(OH) vitamin D levels?

AIM

Assessment of the efficacy of vitamin D replenishment and maintenance doses required to attain optimal levels in boys with Duchenne muscular dystrophy (DMD).

METHOD

25(OH)-vitamin D levels and concurrent vitamin D dosage were collected from retrospective case-note review of boys with DMD at the Dubowitz Neuromuscular Centre. Vitamin D levels were stratified as deficient at <25 nmol/L, insufficient at 25-49 nmol/L, adequate at 50-75 nmol/L and optimal at >75 nmol/L.

RESULT

617 vitamin D samples were available from 197 boys (range 2-18 years)-69% from individuals on corticosteroids. Vitamin D-naïve boys (154 samples) showed deficiency in 28%, insufficiency in 42%, adequate levels in 24% and optimal levels in 6%. The vitamin D-supplemented group (463 samples) was tested while on different maintenance/replenishment doses. Three-month replenishment of daily 3000 IU (23 samples) or 6000 IU (37 samples) achieved optimal levels in 52% and 84%, respectively. 182 samples taken on 400 IU revealed deficiency in 19 (10%), insufficiency in 84 (47%), adequate levels in 67 (37%) and optimal levels in 11 (6%). 97 samples taken on 800 IU showed deficiency in 2 (2%), insufficiency in 17 (17%), adequate levels in 56 (58%) and optimal levels in 22 (23%). 81 samples were on 1000 IU and 14 samples on 1500 IU, with optimal levels in 35 (43%) and 9 (64%), respectively. No toxic level was seen (highest level 230 nmol/L).

CONCLUSIONS

The prevalence of vitamin D deficiency and insufficiency in DMD is high. A 2-month replenishment regimen of 6000 IU and maintenance regimen of 1000-1500 IU/day was associated with optimal vitamin D levels. These data have important implications for optimising vitamin D dosing in DMD.

Fracture in Duchenne Muscular Dystrophy: Natural History and Vitamin D Deficiency

The present study examined the natural history of fracture and vitamin D levels in Duchenne muscular dystrophy patients, who are vulnerable to osteoporosis and fractures. Retrospective analysis of a cohort of 48 Duchenne muscular dystrophy patients revealed that 43% of patients experienced ≥1 fracture. Fracture probabilities at ages 6, 9, 12, and 15 years were 4%, 9%, 31%, and 60% respectively, accelerating around the time of ambulation loss (mean age 11.8 ± 2.7 years). Chronic corticosteroid therapy was utilized in 69% of patients and was associated with all vertebral fractures. A history of vitamin D deficiency occurred in 84%, and 35% were currently deficient. Despite chronic vitamin D supplementation, 38% remained deficient. These results demonstrate that osteoporosis and fracture remain major concerns in Duchenne muscular dystrophy. Bone health should be optimized well before loss of ambulation, however current levels of vitamin D supplementation may be inadequate given high levels of deficiency.

Simvastatin offers new prospects for the treatment of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is the most common and severe inherited neuromuscular disorder. DMD is caused by mutations in the gene encoding the dystrophin protein in muscle fibers. Dystrophin was originally proposed to be a structural protein that protected the sarcolemma from stresses produced during contractions. However, more recently, experimental evidence has revealed a far more complicated picture, with the loss of dystrophin causing dysfunction of multiple muscle signaling pathways, which all contribute to the overall disease pathophysiology. Current gene-based approaches for DMD are conceptually appealing since they offer the potential to restore dystrophin to muscles, albeit a partially functional, truncated form of the protein. However, given the cost and technical challenges facing these genetic approaches, it is important to consider if relatively inexpensive, clinically used drugs may be repurposed for treating DMD. Here, we discuss our recent findings showing the potential of simvastatin as a novel therapy for DMD.

Leptin and metabolic syndrome in patients with Duchenne/Becker muscular dystrophy

OBJECTIVES

To determine whether patients with Duchenne/Becker muscular dystrophy (DMD/BMD) have components of metabolic syndrome (MetSy) and to evaluate whether leptin is associated with components of MetSy.

METHODS

This study included 78 patients (nine, <6 years of age; 54, 6 to <16 years of age; and 15 patients, ≥16 years of age). Obesity and body fat mass were determined by waist circumference and dual-energy X-ray absorptiometry, respectively. A 12-h fasting blood sample was collected in the morning. Patients were categorized into four groups according to the number of criteria for MetSy: group 0: none; group 1: one; group 2: two and group 3: three or more criteria.

RESULTS

All age groups showed components of MetSy. The concentration of these components was significantly higher in patients ≥16 years old. The prevalence of hypertriglyceridemia was from ~37% to 46% in all age groups. The prevalence of MetSy was 7.1% for patients from 6 to <16 years of age and 24% for patients ≥16 years of age. Serum leptin levels increased significantly (P < 0.05) with age; the highest (13.43 ± 9.4 ng/ml) value was observed in patients >16 years of age. Total leptin was correlated with the number of patients with MetSy (r = 0.383; P = 0.001).

CONCLUSIONS

Components of MetSy are significant in patients with DMD/BMD. A high prevalence of hypertriglyceridemia was observed. Younger patients with DMD/BMD have risk factors for MetSy. Although leptin increased according to different degrees of MetSy, this relation disappeared when the body fat was corrected by leptin; therefore, the association could be caused by a common risk factor-fat.

The Performance of the Upper Limb scores correlate with pulmonary function test measures and Egen Klassifikation scores in Duchenne muscular dystrophy

The Performance of the Upper Limb scale was developed as an outcome measure specifically for ambulant and non-ambulant patients with Duchenne muscular dystrophy and is implemented in clinical trials needing longitudinal data. The aim of this study is to determine whether this novel tool correlates with functional ability using pulmonary function test, cardiac function test and Egen Klassifikation scale scores as clinical measures. In this cross-sectional study, 43 non-ambulatory Duchenne males from ages 10 to 30 years and on long-term glucocorticoid treatment were enrolled. Cardiac and pulmonary function test results were analyzed to assess cardiopulmonary function, and Egen Klassifikation scores were analyzed to assess functional ability. The Performance of the Upper Limb scores correlated with pulmonary function measures and had inverse correlation with Egen Klassifikation scores. There was no correlation with left ventricular ejection fraction and left ventricular dysfunction. Body mass index and decreased joint range of motion affected total Performance of the Upper Limb scores and should be considered in clinical trial designs.

Supported Standing in Boys With Duchenne Muscular Dystrophy

PURPOSE

To evaluate the safety, tolerability, and efficacy of supported standing in a small sample of boys with Duchenne muscular dystrophy (DMD).

METHODS

Four 12- to 15-year-old boys with DMD engaged in a home-based supported standing program for 6 to 12 months. A single-subject design was employed to examine muscle length. Bone mineral density was assessed at 4-month intervals using dual-energy x-ray absorptiometry.

RESULTS

Upright, sustained supported standing was tolerated in 3 of the 4 boys. Mean weekly stand times ranged from 1.3 to 3.3 hours. Improved hip or knee flexor muscle length was seen in 3 of the 4 boys. No boys showed improved plantar flexor muscle length or increased lumbar bone mineral density.

CONCLUSIONS

Findings offer preliminary empirical evidence addressing the safety, tolerability, and efficacy of standing in boys with DMD. Additional research with an emphasis on better program adherence is indicated.

Short stature and pubertal delay in Duchenne muscular dystrophy

Children with Duchenne muscular dystrophy (DMD) are shorter than their healthy peers. The introduction of corticosteroid (CS) has beneficial effects on muscle function but slows growth further and is associated with pubertal delay. In contrast to CS usage in most children and adolescents, weaning glucocorticoid is not a key objective of management in DMD. As the outlook for these young people improves, one of the main challenges is to reduce or offset the detrimental effects of CS on growth and development. This is a review of the aetiology and prevalence of short stature and delayed puberty in DMD, a summary of the treatments available and suggestions for areas of further research.

Nutrition Considerations in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a serious degenerative muscular disease affecting males. Diagnosis usually occurs in childhood and is confirmed through genetic testing and/or muscle biopsy. Accompanying the disease are several nutrition-related concerns: growth, body composition, energy and protein requirements, constipation, swallowing difficulties, bone health, and complementary medicine. This review article addresses the nutrition aspects of DMD.

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.

Growth failure and nutrition considerations in chronic childhood wasting diseases

Growth failure is a common problem in many children with chronic diseases. This article is an overview of the most common causes of growth failure/growth retardation that affect children with a number of chronic diseases. We also briefly review the nutrition considerations and treatment goals. Growth failure is multifactorial in children with chronic conditions, including patients with cystic fibrosis, chronic kidney disease, chronic liver disease, congenital heart disease, human immunodeficiency virus, inflammatory bowel disease, short bowel syndrome, and muscular dystrophies. Important contributory factors to growth failure include increased energy needs, increased energy loss, malabsorption, decreased energy intake, anorexia, pain, vomiting, intestinal obstruction, and inflammatory cytokines. Various metabolic and pathologic abnormalities that are characteristic of chronic diseases further lead to significant malnutrition and growth failure. In addition to treating disease-specific abnormalities, treatment should address the energy and protein deficits, including vitamin and mineral supplements to correct deficiencies, correct metabolic and endocrinologic abnormalities, and include long-term monitoring of weight and growth. Individualized, age-appropriate nutrition intervention will minimize the malnutrition and growth failure seen in children with chronic diseases.

[Current care strategies for Duchenne muscular dystrophy]

BACKGROUND

The medical care of patients with Duchenne muscular dystrophy (DMD) is an interdisciplinary and multifaceted task. The vast majority of those affected show a nearly constant course which is reflected in a corresponding stage-oriented treatment concept. Although there is still no causal therapy available for DMD, the course and in particular the quality of life of patients can be decisively improved by established medical practices.

THERAPEUTIC STRATEGIES

The orthopedic problems of DMD patients include contractures of the upper and lower extremities as well as sitting instability due to progressive scoliosis with pelvic imbalance. The orthopedic treatment incorporates conservative measures, such as physiotherapy, provision of orthotic devices and wheelchairs as well as surgery to resolve contractures of the lower extremities and surgical stabilization of the spine. Furthermore, in these patients orthopedic surgeons and trauma surgeons are confronted with the treatment and prophylaxis of fractures induced by osteoporosis. An early onset of glucocorticoid therapy markedly delays the loss of motor abilities.

TREATMENT ASPECTS

An important aspect in the care of DMD patients is the timely prophylaxis and treatment of respiratory insufficiency with regular sessions of breathing therapy, learning breathing and coughing techniques and the sufficiently early start of non-invasive mechanically assisted ventilation. Of similar relevance are also the early recognition and cardioprotective treatment of cardiomyopathy.

CONCLUSION

The orthopedic surgeon accompanies the patient and family through all stages of the disease and must be appropriately informed on current management and treatment strategies even outside the limits of the personal field of specialization.

Observations of body mass index in Duchenne muscular dystrophy: a longitudinal study

BACKGROUND/OBJECTIVES

Nutritional issues that are associated with Duchenne muscular dystrophy (DMD) remain poorly understood. The aim of this analysis was to describe and explore longitudinal observations of body mass index (BMI) in a cohort of children with DMD.

SUBJECTS/METHODS

Anthropometric and clinical characteristics were collected retrospectively and longitudinally for boys with DMD seen in two large neuromuscular clinics. BMI Z-scores were determined using the Centers for Disease Control and Prevention reference values for children (2000).

RESULTS

Medical records (n=193) were examined from which 75% were included for analysis. The mean age of the cohort at the time of data collection was 11.9 years, with 72% of patients currently or previously using steroids. The highest prevalence of obesity based on the BMI Z-score was 50% at the age of 10 years. Longitudinally, BMI Z-scores from the age of 2 to 12 years plot approximately one s.d. above the mean, after which there is a marked and progressive decline. BMI gainers were identified for whom BMI Z-score increased by 1.65 units compared with the 0.09 units in non-gainers. BMI gainers were younger when they had their first BMI measurement (5.9 vs 7.2 years), and this measure was significantly lower compared with the non-gainers (BMI Z-score: 0.04 vs 1.17). In this cohort, BMI was associated with age, ambulatory status and lung function.

CONCLUSIONS

This study demonstrates that boys with DMD using steroid therapy experience shifts in BMI. A declining BMI appears to be associated with increasing age. Interpretation of growth patterns is limited here by a lack of normative growth references in DMD.

Current treatment and management of dystrophinopathies

OPINION STATEMENT

• Duchenne muscular dystrophy (DMD), the most common and severe type of dystrophinopathy, is a progressive disease affecting primordially skeletal and cardiac muscle. A coordinated multidisciplinary approach is required to address its multisystemic manifestations and secondary problems.• Treatment with glucocorticosteroids (GCS) is accepted as standard of care in ambulant DMD. Daily and intermittent administrations are both in common use with different efficacy and different side effect profile.• There are no established guidelines for age/stage at initiation and treatment duration of GCS. Common practice is initiation of GCS before the child is starting to decline (between age 3 and 6 years) and continuation of monitored treatment after loss of ambulation, aiming at delaying cardiac and respiratory manifestations and preventing the development of scoliosis.• Prevention, monitoring, and treatment of the side effects of long-term chronic GCS use, such as excessive weight gain, hypertension, osteoporosis, impairment of glucose metabolism, delayed puberty, and cataract, should be integrated in the standards of care.• Noninvasive ventilatory support associated with cough assisting techniques has significantly improved the longevity in DMD.• Pharmacologic treatment for cardiac manifestations includes the standard treatments of dilated cardiomyopathy and arrhythmia such as the use of angiotensin converting enzyme (ACE) inhibitors, beta-blockers and diuretics. The lack of robust controlled data hampers clear recommendations about preventive treatment with ACE inhibitors.• DMD is associated with low bone mineral content, which is aggravated by the use of corticosteroids. The use of biphosphonates can be considered in the treatment of painful vertebral fractures. The use of biphosphonates as a preventive treatment should be investigated in randomized controlled studies.• DMD has evolved from a pediatric disease to an adult condition. This underscores the need to prepare adult neurologists for the optimal surveillance and management of patients with a severe chronic disease that have outgrown the pediatric care and that may develop new disease manifestations with improved longevity.

Patterns of growth in ambulatory males with Duchenne muscular dystrophy

OBJECTIVE

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.

STUDY DESIGN

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.

RESULTS

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.

CONCLUSION

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.