Real-world experience with gene therapy in Duchenne muscular dystrophy center readiness and patients safety: report from Qatar.

On the basis of strong research evidence, Duchenne muscular dystrophy (DMD), the most common severe childhood form of muscular dystrophy, is an X-linked recessive disorder caused by out-of-frame mutations of the dystrophin gene. Thus, it is classified asa dystrophinopathy. The disease onset is before age 5 years. Patients with DMD present with progressive symmetrical limb-girdle muscle weakness and become wheelchair dependent after age 12 years. (2)(3). On the basis of some research evidence,cardiomyopathy and congestive heart failure are usually seen in the late teens in patients with DMD. Progressive scoliosis and respiratory in sufficiency often develop once wheelchair dependency occurs. Respiratory failure and cardiomyopathy are common causes of death, and few survive beyond the third decade of life. (2)(3)(4)(5)(6)(7). On the basis of some research evidence, prednisone at 0.75 mg/kg daily (maximum dose, 40 mg/d) or deflazacort at 0.9 mg/kg daily (maximum dose, 39 mg/d), a derivative of prednisolone (not available in the United States), as a single morning dose is recommended for DMD patients older than 5 years, which may prolong independent walking from a few months to 2 years. (2)(3)(16)(17). Based on some research evidence, treatment with angiotensin-converting enzyme inhibitors, b-blockers, and diuretics has been reported to be beneficial in DMD patients with cardiac abnormalities. (2)(3)(5)(18). Based on expert opinion, children with muscle weakness and increased serum creatine kinase levels may be associated with either genetic or acquired muscle disorders (Tables 1 and 3). (14)(15)

D.P.15 Quantitative T2 relaxation times in lower leg of Duchenne and Becker muscular dystrophy patients

75th European Neuromuscular Centre International Workshop: 2nd workshop on the treatment of muscular dystrophy 10-12 December, 1999, Naarden, The Netherlands.

Early studies have demonstrated that (total) magnesium was decreased in skeletal muscle of Duchenne muscular dystrophy (DMD) patients. Free intramuscular Mg2+ can be derived from 31 P NMRS measurements. The value of free intramuscular magnesium concentration ([Mg2+ ]) is highly dependent on precise knowledge of intracellular pH, which is abnormally alkaline in dystrophic muscle, possibly due to an expanded interstitial space, potentially causing an underestimation of [Mg2+ ]. We have recently shown that intracellular pH can be derived using 1 H NMRS of carnosine. Our aim was to determine whether 31 P NMRS-based [Mg2+ ] is, in fact, abnormally low in DMD patients, taking advantage of the 1 H NMRS-based pH. A comparative analysis was, therefore, made between [Mg2+ ] values calculated with both 1 H and 31 P NMRS-based approaches to determine pH in 25 DMD patients, on a 3-T clinical NMR scanner. [Mg2+ ] was also assessed with 31 P NMRS only in (forearm or leg) skeletal muscle of 60 DMD patients and 63 age-matched controls. Additionally, phosphodiester levels as well as quantitative NMRI indices including water T2 , fat fraction, contractile cross-sectional area and one-year changes were evaluated. The main finding was that the significant difference in [Mg2+ ] between DMD patients and controls was preserved even when the intracellular pH determined with 1 H NMRS was similar in both groups. Consequently, we observed that [Mg2+ ] is significantly lower in DMD patients compared with controls in the larger database where only 31 P NMRS data were obtained. Significant yet weak correlations existed between [Mg2+ ] and PDE, water T2 and fat fraction. We concluded that low [Mg2+ ] is an actual finding in DMD, whether intracellular pH is normal or alkaline, and that it is a likely consequence of membrane leakiness. The response of Mg2+ to therapeutic treatment remains to be investigated in neuromuscular disorders. Free [Mg2+ ] determination with 31 P NMRS is highly dependent on a precise knowledge of intracellular pH. The pH of Duchenne muscular dystrophy (DMD) patients, as determined by 31 P NMRS, is abnormally alkaline. We have recently shown that intracellular pH could be determined using 1 H NMRS of carnosine, and that intracellular pH was alkaline in a proportion of, but not all, DMD patients with a 31 P NMRS-based alkaline pH. Taking advantage of this 1 H NMRS-based intracellular pH, we found that free intramuscular [Mg2+ ] is in fact abnormally low in DMD patients.

Loss of Dp140 regulatory sequences is associated with cognitive impairment in dystrophinopathies

It is challenging to diagnose suspected Duchenne muscular dystrophy (DMD) patients in the very early stage of the disease. More evidence is needed to demonstrate the potential of quantitative MRI (qMRI) in precisely identifying patients before substantial physical decline occurs. To assess the early diagnostic performance of multi-parametric qMRI for DMD patients, and the ability to identify DMD patients with mild functional decline. Prospective. One hundred and forty DMD subjects (9.0 ± 2.2 years old), 24 male healthy controls (HCs) (9.2 ± 2.5 years old). 3.0 T/3-point Dixon, T1-mapping, and T2-mapping. qMRI measurements (fat fraction [FF], T1, and T2) of 11 thigh muscles (rectus femoris [RF], vastus lateralis [VL], vastus intermedius, vastus medialis, gracilis, sartorius, adductor longus, adductor magnus [AM], semitendinosus, semimembranosus, biceps femoris long head [BFLH]) on the right side were conducted. NorthStar ambulatory assessment (NSAA) score used to evaluate the function of DMD patients and divided them into three subgroups: mild (76-100 score), moderate (51-75 score), and severe (0-50 score) functional decline. Independent t-test, ANOVA analysis, and receiver operating characteristic (ROC) curves. A P-value <0.05 was considered statistically significant. Compared with HCs, FF and T2 were significantly higher in the group of all DMD patients, while T1 was significantly lower. The combination of T1 and T2 in RF, VL, AM, and BFLH achieved excellent area under curve (AUCs) (0.967-0.992) in differentiating five DMD patients without abnormal fat infiltration from HCs. Overall, T2 reached higher AUCs than FF and T1 in distinguishing DMD with mild functional decline from HCs, whereas FF achieved higher AUCs than T1 and T2 in distinguishing three DMD subgroups with functional decline. Multi-parametric qMRI demonstrate effective diagnostic capabilities for DMD patients in the early stage of the disease, and can identify patients with mild physical decline. 2 TECHNICAL EFFICACY: Stage 3.

We aimed to identify novel biomarkers of muscle pathological changes via a large-scale histopathology-based multi-omics study of dystrophinopathies. We performed a comparative pathological analysis of 121 Duchenne muscular dystrophy (DMD) and 114 Becker muscular dystrophy (BMD) patients to determine muscle pathological similarities and differences between DMD and BMD that have not been systematically investigated. Customized bioinformatic analyses of bulk muscle RNA-sequencing data derived from 35 DMD patients, 39 BMD patients, and 21 controls were performed to identify gene signatures associated with pathological changes. Validation experiments, including single-nucleus RNA-sequencing, RNAscope in situ hybridization, and immunofluorescence staining, were performed in a subset of DMD and BMD patients, as well as 27 patients with other acquired and inherited myopathies. Systematic pathological analyses revealed that the percentages of necrotic, regenerating, and hypercontractive myofibers and the degree of muscle fibrosis were greater in DMD patients than in BMD patients. In both DMD and BMD patients, the percentages of necrotic, regenerating, and hypercontractive myofibers respectively increased in the early-stage and decreased in later disease stages, whereas muscle fibrosis progressively worsened with disease progression. Comparative transcriptomic analysis indicated that inflammatory responses were significantly activated in DMD patients compared to BMD patients, which was confirmed by immunohistochemistry analyses. Our customized bioinformatic analyses identified the gene set of MYH3, MYH8, IL17B, TNNT2, MYMK, and TDO2 as the most associated gene signature for muscle necrosis and regeneration. Muscle quantitative reverse transcription-polymerase chain reaction analyses confirmed significantly increased levels of IL17B and TNNT2 mRNA expression in both DMD and BMD patients compared to controls. Muscle IL17B mRNA expression was significantly correlated with histological muscle regeneration and negatively correlated with the age of patients with dystrophinopathy. Single-nucleus RNA-sequencing and RNAscope in situ hybridization demonstrated that IL17B mRNA was expressed in regenerating myofibers of patients with DMD and BMD, as well as in various acquired and inherited myopathies. Immunofluorescence staining further confirmed that interleukin-17B was expressed in regenerating myofibers of DMD and BMD patients. Our study provides evidence that interleukin-17B is a new biomarker of muscle regeneration in dystrophinopathies.

What is the central question of this study? We examined whether the macrophage-synthesized antioxidant 7,8-dihydroneopterin was elevated in Duchenne muscular dystrophy (DMD) patients. We then examined whether 7,8-dihydroneopterin could protect dystrophic skeletal mouse muscle from eccentric contraction-induced force loss and improve recovery. What is the main finding and its importance? Urinary neopterin/creatinine and 7,8-dihydroneopterin/creatinine were elevated in DMD patients. 7,8-Dihydroneopterin attenuated eccentric contraction-induced force loss of dystrophic skeletal mouse muscle and accelerated recovery of force. These results suggest that eccentric contraction-induced force loss is mediated, in part, by an oxidative component and provides a potential protective role for 7,8-dihydroneopterin in DMD. Macrophage infiltration is a hallmark of dystrophin-deficient muscle. We tested the hypothesis that Duchenne muscular dystrophy (DMD) patients would have elevated levels of the macrophage-synthesized pterins, neopterin and 7,8-dihydroneopterin, compared with unaffected age-matched control subjects. Urinary neopterin/creatinine and 7,8-dihydroneopterin/creatinine were elevated in DMD patients, and 7,8-dihydroneopterin/creatinine was associated with patient age and ambulation. Urinary 7,8-dihydroneopterin corrected for specific gravity was also elevated in DMD patients. Given that 7,8-dihydroneopterin is an antioxidant, we then identified a potential role for 7,8-dihydroneopterin in disease pathology. We assessed whether 7,8-dihydroneopterin could: (i) protect against isometric force loss in wild-type skeletal muscle exposed to various pro-oxidants; and (ii) protect wild-type and mdx muscle from eccentric contraction-induced force loss, which has an oxidative component. Force loss was elicited in isolated extensor digitorum longus (EDL) muscles by 10 eccentric contractions, and recovery of force after the contractions was measured in the presence of exogenous 7,8-dihydroneopterin. 7,8-Dihydroneopterin attenuated isometric force loss by wild-type EDL muscles when challenged by H2 O2 and HOCl, but exacerbated force loss when challenged by SIN-1 (NO• , O2• , ONOO- ). 7,8-Dihydroneopterin attenuated eccentric contraction-induced force loss in mdx muscle. Isometric force production by EDL muscles of mdx mice also recovered to a greater degree after eccentric contractions in the presence of 7,8-dihydroneopterin. The results corroborate macrophage activation in DMD patients, provide a potential protective role for 7,8-dihydroneopterin in the susceptibility of dystrophic muscle to eccentric contractions and indicate that oxidative stress contributes to eccentric contraction-induced force loss in mdx skeletal muscle.

Transduction of Full-length Dystrophin to Multiple Skeletal Muscles Improves Motor Performance and Life Span in Utrophin/Dystrophin Double Knockout Mice

Therapeutic Potential of Proteasome Inhibition in Duchenne and Becker Muscular Dystrophies

What Can We Learn From Clinical Trials of Exon Skipping for DMD?

Functional Rescue of Dystrophin-deficient mdx Mice by a Chimeric Peptide-PMO

Circulating Muscle-specific miRNAs in Duchenne Muscular Dystrophy Patients.

P.7.8 The national Dutch dystrophinopathy patient registry

Dystrophin-positive myotubes in innervated muscle cultures from Duchenne and Becker muscular dystrophy patients