VARIANCE OF AGE AT ONSET IN A JAPANESE FAMILY WITH AMYOTROPHIC-LATERAL-SCLEROSIS ASSOCIATED WITH A NOVEL CU/ZN SUPEROXIDE-DISMUTASE MUTATION

Although about 5 to 10% of amyotrophic lateral sclerosis (ALS) cases are familial, the pathophysiology of ALS remains unknown. A new point mutation in exon 4 of the Cu/Zn superoxide dismutase (SOD) gene, resulting in an amino acid substitution of leucine(84) by valine (L84V), in a Japanese patient with familial ALS (FALS) was identified. This L84V substitution was not observed in 57 normal Japanese control subjects. The enzymatic activities of Cu/Zn SOD of skin fibroblasts were significantly reduced to 75% of the control level in the affected patient. The progression of the disease with this mutation is very rapid, but-the age at onset varies with sex or generation within a family.