A female carrier of spinal and bulbar muscular atrophy diagnosed with DNAJB6-related distal myopathy

Mutations in the DNAJB6 gene cause limb girdle muscular dystrophy D1 (LGMD D1) and distal myopathy with rimmed vacuoles. With the discovery of new mutations, the phenotypic spectrum of DNAJB6-related myopathy has been extended, making the diagnosis more complicated. In this study, we describe a female carrier of spinal and bulbar muscular atrophy (SBMA) diagnosed with DNAJB6-related distal myopathy. The c.292_294delGAT (p. Asp98del) mutation in the DNAJB6 gene and a 49 CAG repeat expansion in the androgen receptor (AR) gene were identified. According to the clinical manifestations of distal-dominant lower limb involvement, a myogenic pattern in the electrophysiological study, and rimmed vacuoles on muscle pathology, the patient was ultimately diagnosed with DNAJB6-related distal myopathy. A functional study in a zebrafish model indicated that the c.292_294delGAT (p. Asp98del) mutation contributed to muscle structure defects. This study offers useful insights for the differential diagnosis of a condition in which patients carry pathogenic variants in different genes.

Automated summary

This study describes a female carrier of spinal and bulbar muscular atrophy (SBMA) who was diagnosed with DNAJB6-related distal myopathy. Through clinical manifestations, electrophysiological study, and muscle pathology, the patient was ultimately diagnosed with DNAJB6-related distal myopathy. Functional study in a zebrafish model revealed that the mutation contributed to muscle structure defects.