Skeletal muscle regeneration by muscle satellite cells is a physiological mechanism activated upon muscle damage and regulated by Notch signaling. In a family with autosomal recessive limb‐girdle muscular dystrophy, we identified a missense mutation in POGLUT1 (protein O‐glucosyltransferase 1), an enzyme involved in Notch posttranslational modification and function. In vitro and in vivo experiments demonstrated that the mutation reduces O‐glucosyltransferase activity on Notch and impairs muscle development. Muscles from patients revealed decreased Notch signaling, dramatic reduction in satellite cell pool and a muscle‐specific α‐dystroglycan hypoglycosylation not present in patients' fibroblasts. Primary myoblasts from patients showed slow proliferation, facilitated differentiation, and a decreased pool of quiescent PAX7+ cells. A robust rescue of the myogenesis was demonstrated by increasing Notch signaling. None of these alterations were found in muscles from secondary dystroglycanopathy patients. These data suggest that a key pathomechanism for this novel form of muscular dystrophy is Notch‐dependent loss of satellite cells.

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Background and purpose Prognosis of myasthenia gravis (MG) in patients with thymoma is not well established. Moreover, it is not clear whether thymoma recurrence or unresectable lesions entail a worse prognosis of MG. Methods This multicenter study was based on data from a Spanish neurologist‐driven MG registry. All patients were aged >18 years at onset and had anti‐acetylcholine receptor antibodies. We compared the clinical data of thymomatous and nonthymomatous patients. Prognosis of patients with recurrent or nonresectable thymomas was assessed. Results We included 964 patients from 15 hospitals; 148 (15.4%) had thymoma‐associated MG. Median follow‐up time was 4.6 years. At onset, thymoma‐associated MG patients were younger (52.0 vs. 60.4 years, p < 0.001), had more generalized symptoms (odds ratio [OR]: 3.02, 95% confidence interval [CI]: 1.95–4.68, p < 0.001) and more severe clinical forms according to the Myasthenia Gravis Foundation of America (MGFA) scale (OR: 1.6, 95% CI: 1.15–2.21, p = 0.005). Disease severity based on MGFA postintervention status (MGFA‐PIS) was higher in thymomatous patients at 1 year, 5 years, and the end of follow‐up. Treatment refractoriness and mortality were also higher (OR: 2.28, 95% CI: 1.43–3.63, p = 0.001; hazard ratio: 2.46, 95% CI: 1.47–4.14, p = 0.001). Myasthenic symptoms worsened in 13 of 27 patients with recurrences, but differences in long‐term severity were not significant. Fifteen thymomatous patients had nonresectable thymomas with worse MGFA‐PIS and higher mortality at the end of follow‐up. Conclusions Thymoma‐associated MG patients had more severe myasthenic symptoms and worse prognosis. Thymoma recurrence was frequently associated with transient worsening of MG, but long‐term prognosis did not differ from nonrecurrent thymoma. Patients with nonresectable thymoma tended to present severe forms of MG.

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Background: Effectiveness of cladribine tablets, an oral disease-modifying treatment (DMT) for multiple sclerosis (MS), was established in clinical trials and confirmed with real-world experience. Objectives: Use real-world data to compare treatment patterns and clinical outcomes in people with MS (pwMS) treated with cladribine tablets versus other oral DMTs. Methods: Retrospective treatment comparisons were based on data from the international MSBase registry. Eligible pwMS started treatment with cladribine, fingolimod, dimethyl fumarate, or teriflunomide tablets from 2018 to mid-2021 and were censored at treatment discontinuation/switch, death, loss to follow-up, pregnancy, or study period end. Treatment persistence was evaluated as time to discontinuation/switch; relapse outcomes included time to first relapse and annualized relapse rate (ARR). Results: Cohorts included 633 pwMS receiving cladribine tablets, 1195 receiving fingolimod, 912 receiving dimethyl fumarate, and 735 receiving teriflunomide. Individuals treated with fingolimod, dimethyl fumarate, or teriflunomide switched treatment significantly more quickly than matched cladribine tablet cohorts (adjusted hazard ratio (95% confidence interval): 4.00 (2.54–6.32), 7.04 (4.16–11.93), and 6.52 (3.79–11.22), respectively). Cladribine tablet cohorts had significantly longer time-to-treatment discontinuation, time to first relapse, and lower ARR, compared with other oral DMT cohorts. Conclusion: Cladribine tablets were associated with a significantly greater real-world treatment persistence and more favorable relapse outcomes than all oral DMT comparators.