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Adeno-associated virus (AAV)-based gene therapies are emerging strategies in Duchenne muscular dystrophy (DMD) treatment. Exposure to wild-type AAV can lead to development of neutralizing antibodies (NAbs) and blocking of AAV transduction, thereby limiting the delivery of AAV vector-based gene therapy. Therefore, it is imperative to check for the presence of AAV NAbs in a patient who is a candidate for gene therapy. We prospectively enrolled 101 genetically confirmed males with DMD (median age 11 years, 48% ambulatory and 59% on steroids) and performed AAV neutralization assays against AAV2, AAV8, AAV9, and AAVrh74 serotypes. The serotype analysis showed that AAV9 (36%) and AAVrh74 (32%) seroprevalence was lower compared with AAV2 (56%) and AAV8 (47%). Interestingly, age was not correlated with NAb titer for any of the capsids. NAb responses were observed at a higher frequency in African American participants and at a lower frequency in Caucasian participants for all four serotypes. Further analysis showed no significant differences in NAb titers regardless of serotype and whether participants were taking steroids or not. Finally, we observed higher AAV8, AAV9, and AAVrh74 seroprevalence and significantly higher AAV2 and AAV8 NAb titers in participants who were ambulatory compared with nonambulatory participants. Overall, these data identify AAV9 and AAVrh74 as the two serotypes with lower pre-existing NAb titers in this study's cohort of 101 males with DMD, possibly showing their utility in future gene therapy applications in treatment of this cohort of patients with DMD. [ABSTRACT FROM AUTHOR]

Objective: There is limited and mixed research describing the memory performance of boys with Duchenne muscular dystrophy (DMD), a progressive disorder that affects the muscle and the brain, presumably due to the absence of dystrophin; however, the literature indicates either the existence of a selective deficit in verbal working memory, or more generalized impairment in both verbal and visual memory. Far less is documented about the neurocognitive profile of boys with Becker muscular dystrophy (BMD), a closely related neuromuscular disorder which allows for at least some functional dystrophin protein to circulate. The Child and Adolescent Memory Profile (ChAMP) is a valid and widely used memory battery that has not been studied in either DMD or BMD. This study aimed to assess the verbal and visual memory performance in boys having either a DMD or a BMD diagnosis using the ChAMP. A working memory measure, the Digit Span subtest from the Wechsler Intelligence Scale for Children-Fifth Edition, was also included for comparison. Participants and Methods: Twenty-one patients (Age M = 12.19 ± 3.60; 100% male; 76% DMD, 24% Becker) were selected from retrospective data collection of neuropsychological performance in children with neuromuscular disorders. Patients were recruited and assessed as part of a larger scale IRB-approved research study designed to better understand the neurocognitive and behavioral trajectories of boys with DMD or BMD with a complete neuropsychological battery. Results: Independent samples f-tests revealed no significant differences between groups across verbal (DMD M = 88.71; BMD M = 100.80; p =.08), visual (DMD M =90.36; BMD M 93.60; p =.33), and working memory (DMD M = 84.69; BMD: M 82.60; p =.40) domains. In additional analyses, a one sample f-test comparing verbal and visual memory within DMD children revealed significantly worse verbal than visual memory scores (verbal memory M = 88.71; visual memory M = 90.36; p = <.001). Conclusions: There were no significant differences between groups in verbal, visual, and working memory performance, though sample size was a significant limitation. However, based on a comparison of means, children with BMD appear to have stronger verbal memory skills than children with DMD. Furthermore, significant differences between verbal and visual memory within DMD children were observed, such that verbal memory skills were weaker. These findings add to the absence of literature on verbal and visual memory outcomes in children with DMD and BMD. [ABSTRACT FROM AUTHOR]

Introduction: This study's objective was to evaluate quantitative electromyography (QEMG) using multiple-motor-unit (multi-MUP) analysis in Duchenne muscular dystrophy (DMD).Methods: Ambulatory DMD boys, aged 5-15 years, were evaluated with QEMG at 6-month intervals over 14 months. EMG was performed in the right biceps brachii (BB) and tibialis anterior (TA) muscles. Normative QEMG data were obtained from age-matched healthy boys. Wilcoxon signed-rank tests were performed.Results: Eighteen DMD subjects were enrolled, with a median age of 7 (interquartile range 7-10) years. Six-month evaluations were performed on 14 subjects. QEMG showed significantly abnormal mean MUP duration in BB and TA muscles, with no significant change over 6 months.Conclusions: QEMG is a sensitive electrophysiological marker of myopathy in DMD. Preliminary data do not reflect a significant change in MUP parameters over a 6-month interval; long-term follow-up QEMG studies are needed to understand its role as a biomarker for disease progression. Muscle Nerve 56: 1361-1364, 2017. [ABSTRACT FROM AUTHOR]

The article discusses an inherited X-linked recessive disorder called duchenne muscular dystrophy (DMD) which involves symmetric muscle weakness and gait disturbance with onset in early childhood. It states that muscle diseases in clinical practice can be screened through creatine kinase (CK) because its levels increase in condition with active muscle fiber necrosis and injury. The differential diagnosis of the disease, the use of glucocorticoids for treatment and the long-term management of comorbid conditions are also noted.