Duchenne and Becker muscular dystrophy (DMD/BMD), caused by mutations in the DMD gene, are characterized by the presence of progressive muscle weakness. DMD is the most severe form of the disease, leading to significant disability, and is the most common neuromuscular disorder in childhood. For these patients, it is essential to obtain a precise genetic diagnosis to offer them appropriate genetic and reproductive counselling and be eligible to gene therapies. However, up to 7% of patients with DMD/BMD remain genetically undiagnosed after genetic testing in the clinical practice. In this work we evaluate the presence of alterations in the mRNA of the DMD gene in undiagnosed DMD/BMD patients and we report new findings that could facilitate the diagnosis in future patients.   (By Alba Segarra Casas, https://jmg.bmj.com/content/early/2022/12/18/jmg-2022-108828 )