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Background: Dilated cardiomyopathy (DCM) is a major complication of, and leading cause of mortality in Duchenne muscular dystrophy (DMD). Its severity, age at onset, and rate of progression display wide variability, whose molecular bases have been scarcely elucidated. Potential DCM-modifying factors include glucocorticoid (GC) and cardiological treatments, DMDmutation type and location, and variants in other genes.Methods and Results: We retrospectively collected 3138 echocardiographic measurements of left ventricular ejection fraction (EF), shortening fraction (SF), and end-diastolic volume (EDV) from 819 DMD participants, 541 from an Italian multicentric cohort and 278 from the Cooperative International Neuromuscular Group Duchenne Natural History Study (CINRG-DNHS). Using generalized estimating equation (GEE) models, we estimated the yearly rate of decrease of EF (–0.80%) and SF (–0.41%), while EDV increase was not significantly associated with age. Utilizing a multivariate generalized estimating equation (GEE) model we observed that mutations preserving the expression of the C-terminal Dp71 isoform of dystrophin were correlated with decreased EDV (–11.01?mL/m2, p?=?0.03) while for dp116 were correlated with decreased EF (–4.14%, p?=?<0.001). The rs10880 genotype in the LTBP4gene, previously shown to prolong ambulation, was also associated with increased EF and decreased EDV (+3.29%, p?=?0.002, and –10.62?mL/m2, p?=?0.008) with a recessive model.Conclusions: We quantitatively describe the progression of systolic dysfunction progression in DMD, confirm the effect of distal dystrophin isoform expression on the dystrophin-deficient heart, and identify a strong effect of LTBP4genotype of DCM in DMD.

Evidence on the long-term efficacy of steroids in Duchenne muscular dystrophy (DMD) after loss of ambulation is limited. Characterize and compare disease progression by steroid treatment (prednisone, deflazacort, or no steroids) among non-ambulatory boys with DMD. Disease progression was measured by functional status (Performance of Upper Limb Module for DMD 1.2 [PUL] and Egen Klassifikation Scale Version 2 [EK] scale) and by cardiac and pulmonary function (left ventricular ejection fraction [LVEF], forced vital capacity [FVC] % -predicted, cough peak flow [CPF]). Longitudinal changes in outcomes, progression to key disease milestones, and dosing and body composition metrics were analyzed descriptively and in multivariate models. This longitudinal cohort study included 86 non-ambulatory patients with DMD (mean age 13.4 years; n = 40 [deflazacort], n = 29 [prednisone], n = 17 [no steroids]). Deflazacort use resulted in slower average declines in FVC % -predicted vs. no steroids (+3.73 percentage points/year, p < 0.05). Both steroids were associated with significantly slower average declines in LVEF, improvement in CPF, and slower declines in total PUL score and EK total score vs. no steroids; deflazacort was associated with slower declines in total PUL score vs. prednisone (all p < 0.05). Both steroids also preserved functional abilities considered especially important to quality of life, including the abilities to perform hand-to-mouth function and to turn in bed at night unaided (all p < 0.05 vs. no steroids). Steroid use after loss of ambulation in DMD was associated with delayed progression of important pulmonary, cardiac, and upper extremity functional deficits, suggesting some benefits of deflazacort over prednisone.

Becker muscular dystrophy is an X-linked, genetic disorder causing progressive degeneration of skeletal and cardiac muscle, with a widely variable phenotype. A 3-year, longitudinal, prospective dataset contributed by patients with confirmed Becker muscular dystrophy was analyzed to characterize the natural history of this disorder. A better understanding of the natural history is crucial to rigorous therapeutic trials. A cohort of 83 patients with Becker muscular dystrophy (5–75 years at baseline) were followed for up to 3 years with annual assessments. Muscle and pulmonary function outcomes were analyzed herein. Age-stratified statistical analysis and modeling were conducted to analyze cross-sectional data, time-to-event data, and longitudinal data to characterize these clinical outcomes. Deletion mutations of dystrophin exons 45–47 or 45–48 were most common. Subgroup analysis showed greater pairwise association between motor outcomes at baseline than association between these outcomes and age. Stronger correlations between outcomes for adults than for those under 18 years were also observed. Using cross-sectional binning analysis, a ceiling effect was seen for North Star Ambulatory Assessment but not for other functional outcomes. Longitudinal analysis showed a decline in percentage predicted forced vital capacity over the life span. There was relative stability or improved median function for motor functional outcomes through childhood and adolescence and decreasing function with age thereafter. There is variable progression of outcomes resulting in significant heterogeneity of the clinical phenotype of Becker muscular dystrophy. Disease progression is largely manifest in adulthood. There are implications for clinical trial design revealed by this longitudinal analysis of a Becker natural history dataset.

Duchenne muscular dystrophy (DMD) patients experience skeletal muscle degeneration, including respiratory muscles. Respiratory decline in glucocorticoid-treated DMD patients, measured by percent predicted forced vital capacity (FVC% p), is typically 5% annually in patients aged 10 to 18 years. Evaluate the effects of eteplirsen on FVC% p annual change in 3 trials versus matched Cooperative International Neuromuscular Research Group Duchenne Natural History Study (CINRG DNHS) controls. Eteplirsen studies 201/202 evaluated eligible ambulatory DMD patients for at least 4 years, study 204 evaluated primarily non-ambulatory DMD patients for 2 years, and ongoing study 301 is evaluating ambulatory DMD patients for 2 years (interim analysis is included). Eteplirsen-treated patients (n = 74) were amenable to exon 51 skipping and were receiving glucocorticoids. Three CINRG DNHS cohorts included: glucocorticoid-treated patients amenable to exon 51 skipping (Exon 51 CINRG DNHS; n = 20), all glucocorticoid-treated CINRG patients (All CINRG DNHS; n = 172), and all glucocorticoid-treated genotyped CINRG DNHS patients (Genotyped CINRG DNHS; n = 148). FVC% p assessments between ages 10 and <18 years were included for all patients; mixed-model analyses characterized FVC% p annual change. FVC% p annual change was greater for CINRG DNHS Exon 51 controls (– 6.00) versus patients in studies 201/202, study 204, and study 301 (– 2.19, P < 0.001; – 3.66, P0.004; and – 3.79, P0.017, respectively). FVC% p annual change in all eteplirsen studies suggested treatment benefit compared with the Genotyped CINRG DNHS (– 5.67) and All CINRG DNHS (– 5.56) cohorts (P < 0.05, all comparisons). Significant, clinically meaningful attenuation of FVC%p decline was observed in eteplirsen-treated patients versus CINRG DNHS controls.