The p.S59L CHCHD10 variant has been associated with a variety of syndromes, including motor neuron disease and/or (unspecified) dementia plus, in some subjects, cerebellar ataxia.17 Here we identified this variant in a bvFTD subject (21854) without signs of ALS or other NDD, thus reporting the first pure FTD phenotype of the p.S59L CHCHD10 variant, and demonstrating that insults in mitochondrial proteins can lead to pure FTD (for MRI and pedigree, see Figure 3d–f; for a more detailed subject description, see Supplementary Material S6). The gene discussed is CHCHD10; the disease is frontotemporal dementia.