Given that the I114T SOD1 allele shows incomplete penetrance (Lopate et al., 2010) and the L17P FIG4 allele has previously only been associated with CMT4J in combination with a null allele (Nicholson et al., 2011), it raises the possibility that an interaction with the SARM1 GoF alleles is critical for pathogenesis in these ALS cases. This evidence concerns the gene FIG4 and amyotrophic lateral sclerosis.