The aggregates can be formed intracellularly, as is the case with α-synuclein (Parkinson's disease), SOD (superoxide dismutase) (in ALS) and huntingtin (Huntington's disease) [43] or extracellularly, as is the case in prion diseases [48,49], Type 2 diabetes [due to the aggregation of the IAPP (islet amyloid polypeptide)] [50,51] and AD [43]. The gene discussed is IAPP; the disease is Parkinson disease.