Expanding the spectrum of hereditary neuropathies caused by BSCL2 gene mutation: case report

Background Distal hereditary motor neuropathies (dHMN) are genetically heterogeneous group of inherited disorders caused by a gradual progressive degeneration of the motor neuron, resulting in isolated distal muscle weakness and atrophy without sensory involvement. A clinical and genetic overlap between dHMN and Charcot Marie Tooth type 2 (CMT2) is not uncommon. In this article, we reported a rarely described presentation associated with a pathogenic variant in BSCL2 gene. This presentation was thought to be a characteristic of Asian population. Case presentation : We described an Egyptian patient harbored a pathogenic variant in BSCL2 (p.S90L) and presented with an overlapping phenotype of overlapping Silver syndrome and dHMN. However, the presence of subclinical electrophysiological and histopathological sensory abnormalities, a finding previously reported only in Asian patients, has changed the diagnosis into BSCL2-related CMT2. Conclusion Although seipinopathy has traditionally been considered as an isolated motor neuropathy, the BSCL2 (p.S90L) variant has been associated with mild sensory abnormalities in patients from different ethnic backgrounds, not only Asian patients as was proposed previously. Furthermore, we postulate that sensory involvement in dHMN is underrecognized, with considerable overlap with other axonal sensorimotor neuropathies.