Rapid Progression of Sporadic ALS in a Patient Carrying SOD1 p.Gly13Arg Mutation

Amyotrophic lateral sclerosis (ALS), the most common adult onset motor neuron disease, is pathologically characterized by progressive loss of the upper and lower motor neurons. Mutations in the Cu/Zn superoxide dismutase gene (SOD1) account for about 20% of familial ALS cases and a small percentage of sporadic ALS (SALS) cases, and have revealed a validated genotype-phenotype correlation. Herein, we report a p.Gly13Arg mutation in SOD1 exon 1 in a patient with SALS who presented with a rapidly progressive course, predominantly affecting the lower motor neurons. A 48-year-old man presented with progressive weakness and muscle atrophy of the left upper and lower limbs, followed by muscle fasciculation and cramping. The clinical features of the patient were clearly suggestive of ALS, and implied a sporadic form with rapid progression, predominantly affecting the lower motor neurons. Sequencing of the SOD1 gene by PCR revealed a missense mutation of G to C (c.37G>C) in exon 1, and amino acid substitution of glycine by arginine (p.Gly13Arg). This is the first case identifying the p.Gly13Arg mutation of SOD1 in the Korean population, and clinical assessments of this patient revealed a different phenotype compared with other cases.