In FTD, aggregates of microtubule associated protein tau (MAPT), tar DNA-binding protein-43 (TDP43) or fused in sarcoma (FUS) are present in the brain; whereas in AD, aggregates of amyloid-β peptides or neurofibrillary tangles (composed of tau) are present in the brain. The gene discussed is MAPT; the disease is Alzheimer disease.