ELP3 and amyotrophic lateral sclerosis: In an additional study of genes that modify the course of disease in individuals carrying repeat expansions of C9ORF72, the most common cause of familial ALS, single nucleotide polymorphisms (SNPs) in ELP3 reduced the percentage of patients alive eight years after disease onset from ~58% in controls, to ~12% in patients carrying a minor ELP3 SNP23.