• amylotrophic lateral sclerosis
• superoxide dismutase

A myotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterised by the degeneration of motor neurons in the spinal cord, brain stem, and motor cortex, resulting in paralysis of limb, bulbar, and respiratory muscles. About 10% of ALS show a familial trait, and up to 20% of familial ALS is caused by missense mutations of Cu/Zn superoxide dismutase (SOD1). More than 70 mutations have been reported, including a mutation hotspot at codon 93.¹ Mice expressing human mutant SOD1 develop age dependent ALS-like neurological symptoms and pathological features of motor neuron degeneration and cytoplasmic inclusions consisting of mutant SOD1. Patients with SOD1 mutations represent divergent phenotypes, including age of onset, duration of disease, and clinical symptoms, mostly depending on the nature of SOD1 mutation. Acceleration of the age of onset in successive generations called anticipation has been reported in the missense mutations at codon 84 (L84F and L84V) in the SOD1 mutations in Japan, the United States, and Italy.² We experienced anticipation of age at onset in Japanese families with SOD1-G93S mutation. In the families …