Neurofibrillary tangles (Human Phenotype Ontology identifier HP_0002185) is pathological protein aggregates formed by hyperphosphorylation of a microtubule-associated protein known as tau, causing it to aggregate in an insoluble form. Also known as: NFTs, Neurofibrillary tangles composed of disordered microtubules in neurons, Paired helical filaments, Tau-positive neurofibrillary tangles, Tau-positive tangle.