A late-onset phenotype of familial Becker muscular dystrophy with DMD exon 26–34 deletion: a case report

Becker muscular dystrophy is a rare, progressive neuromuscular disease normally associated with an in-frame deletion in the DMD gene. Symptoms of BMD typically appear in late childhood to early adulthood, with slower progression compared to DMD. Given its initial presentation with lower limb weakness, it is challenging to distinguish BMD from other neuromuscular diseases. We report a case of a 63-year-old man who developed weakness in the pelvic girdle and both lower limbs over the past few years. After multiple unsuccessful visits to other medical facilities, the patient came to our hospital. Based on the patient’s symptoms, prior medical history, and his family members’ symptoms, we performed relevant genetic testing, which suggested that the patient has Becker muscular dystrophy associated with the DMD gene. We report a rare case of late-onset Becker muscular dystrophy associated with an in-frame deletion of exons 26–34 in the DMD gene. This case expands the phenotypic spectrum of BMD linked to this specific deletion. It highlights the importance of considering BMD in the differential diagnosis of adult patients with chronic lower-limb weakness.