The dominant inheritance pattern of C9orf72 ALS/FTD, the nonappearance of ALS or FTD patients with missense mutations or null alleles in the C9orf72 gene, and the absence of a neurodegeneration phenotype in most of C9orf72−/− mice (as discussed above) have argued against the loss of C9orf72 function theory as the single mechanism of the disease. The gene discussed is C9orf72; the disease is frontotemporal dementia.