C9orf72 and frontotemporal dementia: Furthermore, our findings together with the previous studies support the idea that the haploinsufficiency, taking place in the FTD and ALS patients carrying the C9orf72 HRE and resulting in the decreased C9orf72 levels, may contribute to defective autophagy and accumulation of, e.g., aggregated TDP-43 and DPR proteins, which represent the typical pathological hallmark changes in the CNS of the C9orf72 HRE carriers.