APOE and Parkinson disease: Other biomarkers (APOE, NTRK2, SLCO1B3, SLC28A3, AQP10, SNCAIP, ANO2, CADM1, PTPRD, GPR32, GPR321, SQOR, SULT1C2, GABRG2, CYP4Z1, CDH13, and FANCF) have been found underlying the clinical traits of PD, including age at onset, cognitive progression, motor progression, composite progression, and tremor dominant and postural instability gait difficulty.