Accordingly, we see usefulness for a broad repertoire of genetically engineered mice carrying disabling mutations such as in the Klotho locus [69,70] and XPF and ERCC1 deficiencies [71], or those developing an ALS-like phenotype due to loss-of-function mutations corresponding to SOD1, TDP-43, and FUS mutations or C9ORF72 repeat expansions in humans [72,73,74,75]. The gene discussed is C9orf72; the disease is amyotrophic lateral sclerosis.