Becker Muscular Dystrophy (BMD) was first described in 1955 by Peter Emil Becker,1 and has been the subject of recent interest2 including a study by Janneke van den Bergen and colleagues.3 The dystrophin gene and protein were discovered 25 years ago.4 They have been intensively investigated at both the clinical and basic research level since with 6000 publications currently recorded in PubMed. A large number of different mutations (exon deletions, duplications and point mutations) are known to cause either severe Duchenne muscular dystrophy (DMD) or the milder allelic BMD, and more than 10 000 patients are recorded in locus-specific databases and patient registries. Generally, DMD patients show a complete absence of dystrophin protein in skeletal muscle, while BMD patients produce some protein, although with lower abundance or functionality. Frequently, the middle part of the dystrophin protein, the so-called rod domain, is truncated in BMD, but the C-terminal and the N-terminal domains are preserved providing binding to actin and to α-dystroglycan among other proteins. The study by van den Bergen and colleagues³ provides an in-depth clinical characterisation of patients with BMD in the Netherlands.

Despite the level of research activity, several fundamental questions about dystrophin and DMD remain …