Asymmetric Distal-Onset GNE Myopathy Mimicking Peripheral Neuropathy: A Case Report

GNE myopathy is a rare autosomal recessive distal myopathy classically characterized by symmetrical distal muscle weakness with relative quadriceps sparing. However, phenotypic variability, including asymmetric onset, may obscure the diagnosis and mimic neuropathic disorders.

A 27-year-old Bangladeshi man presented with a 2-year history of progressive distal weakness, initially involving the left lower limb and later affecting the contralateral limb and distal upper extremities. Neurological examination revealed asymmetric distal weakness with bilateral foot drop and preserved sensory function. Serum creatine kinase was moderately elevated (892 U/L). Nerve conduction studies showed preserved sensory responses with reduced motor amplitudes, while electromyography demonstrated a distal-predominant myopathic pattern. Magnetic resonance imaging of the spine was unremarkable. Clinical exome sequencing identified a homozygous likely pathogenic variant in the GNE gene NM_005476.7:c.484C>T (p.Arg162Cys), confirming the diagnosis.

This case highlights an asymmetric presentation of GNE myopathy mimicking peripheral neuropathy. Recognition of such phenotypic variability and integration of clinical, electrophysiological, and genetic findings are crucial for accurate diagnosis and to avoid misclassification as a neuropathic disorder.