Frontotemporal dementia is clinically and pathologically heterogeneous,8 and recent work has recognized systematic variation in pathological features of TDP-43 underlying FTD.9 ALS also exhibits substantial clinical heterogeneity10; whilst ALS is primarily characterized as a neuromuscular disorder, approximately 20% of ALS cases also have cognitive impairment,11 and/or a typical FTD-syndrome. The gene discussed is TARDBP; the disease is frontotemporal dementia.