An elegant study of Han et al. [65] showed that some autoantibody biomarkers (for example: ICAM4, Myotilin, Fibronectin 1, Pentatricopeptide repeat domain 2) can distinguish PD and health controls, multiple sclerosis, Alzheimer disease and cancer with 90–100% accuracy. The gene discussed is PTCD2; the disease is Parkinson disease.