Other than the p.Asn86Ser mutation, the only other SOD1 mutations ever reported in the homozygous state in ALS patients are p.Leu84Phe, p.Asp90Ala, and p.Leu117Val.10,12,29 The sum of data in families harboring these mutations do not definitively show that mutations in the homozygous state result in a more severe phenotype. This evidence concerns the gene SOD1 and amyotrophic lateral sclerosis.