D90A HETEROZYGOSITY IN THE SOD1 GENE IS ASSOCIATED WITH FAMILIAL AND APPARENTLY SPORADIC AMYOTROPHIC-LATERAL-SCLEROSIS

All mutations in the SOD1 gene associated with familial ALS behave as dominant traits. One mutation, however, giving rise to an aspartic aci d to alanine substitution in codon 90 (D90A), was reported only to ind uce motor neuron disease in homozygous individuals in the Scandinavian population. We describe two families with ALS and one apparently spor adic ALS patient who are heterozygous for the D90A mutation. One patie nt had the unusual phenotype of focal nonprogressing motor neuron dise ase.