DNAJB6 myopathy: a vacuolar myopathy with childhood onset

Abstract

Introduction: DNAJB6 mutations cause an autosomal dominant myopathy that can manifest as limb-girdle muscular dystrophy (LGMD1D/1E) or distal-predominant myopathy. In the majority of patients this myopathy manifests in adulthood and shows vacuolar changes on muscle biopsy.

Methods: Clinical, electrophysiological, pathological, and molecular findings are reported.

Results: We report a 56-year-old woman, who, like 3 other family members, became symptomatic in childhood with slowly progressive limb-girdle muscle weakness, normal serum creatine kinase (CK) values, and myopathic electromyographic findings. Muscle biopsy showed vacuolar changes and congophilic inclusions, and molecular analysis revealed a pathogenic mutation in the DNAJB6 gene. Differences and similarities with previously described cases are assessed.

Conclusions: Childhood-onset of DNAJB6 myopathy is more frequent than previously believed; congophilic inclusions may be present in the muscle of these patients.

Keywords: DNAJB6; LGMD1D; LGMD1E; congophilic inclusions; limb-girdle muscular dystrophy; vacuolar myopathy.