Phenotype in an Infant with SOD1 Homozygous Truncating Mutation

In a child with a homozygous truncating mutation in SOD1, SOD1 activity in red cells was absent and fibroblasts grew only with oxygen deprivation. There was predominant impairment of upper motor neurons, a trait that has led to caution against severe SOD1 suppression in clinical trials involving patients with amyotrophic lateral sclerosis.