An unusual variant of Becker muscular dystrophy

Abstract

We report on 5 brothers with slowly progressive limbgirdle weakness. Calf hypertrophy was absent. The levels of creatine kinase, electromyography, and findings from a muscle biopsy specimen were compatible with muscular dystrophy. The propositus's biopsy specimen also showed numerous rimmed vacuoles. DNA analysis revealed a deletion in the dystrophin gene, establishing a diagnosis of Becker muscular dystrophy. Both the absence of calf hypertrophy and the presence of rimmed vacuoles are unusual features in this disorder.

Rimmed Vacuoles in Becker Muscular Dystrophy Have Similar Features with Inclusion Myopathies

“…In our series, the deletions in exons 45–47 or 45–48 in DMD gene were frequently found in the patients with RV. Our BMD with RV patients also showed a mild course of disease, with later onset and mild elevation of CK, similar as previous reports on the patients with the same deletion on DMD gene [6]. Additionally, in spite of similar age of disease onset in the patients with and without RV with the deletions in exons 45–47 or 45–48, the higher mean biopsy age in the patients with RV may suggest that the milder clinical course and longer disease duration in dystrophinopathy could contributory for the formation of RV in muscle.…”

“…An increase in the number of small atrophic fibers in BMD patients with RV was remarkable as that in the patient who is previously reported [6]. This characteristic pathology is rather like myopathic changes as observed in other late-onset chronic myopathies [20].…”

“…Deletion of exons 45–55, for example, has been reported to be associated with quite mild muscle weakness [18]–[19]. Interestingly, in a previous report, one BMD patient who showed RV in his skeletal muscle section had a deletion from exons 45–48 in the DMD gene and showed mild to moderate weakness in lower girdle muscles [6]. In our series, the deletions in exons 45–47 or 45–48 in DMD gene were frequently found in the patients with RV.…”

“…BMD patients show a wide variety of symptoms from gait disturbance in early childhood to almost no weakness even in adulthood. Through our muscle repository, we noted that some dystrophinopathies also show RVs in the muscles, albeit rare [6]. Because dystrophinopathies are related to membrane fragility of myofibers, the presence of RVs in BMD patients is perplexing and raises several issues that need to be clarified, like the relevance of RVs in BMD and the frequency of BMD patients that show RVs in myofibers.…”

Autosomal dominant limb-girdle muscular dystrophy

“…[28][29] However, rimmed vacuoles without the characteristic filaments are frequent nonspecific findings in different muscle disorders, including forms of LGMD1 7,30 and primary dystrophinopathies. 31 We excluded linkage to the identified loci for the identified loci of autosomal recessive and dominant HIBM. [15][16] We interpreted the mitochondrial proliferation in one patient's muscle as a secondary phenomenon.…”