COMT and Parkinson disease: Additionally, several potential genetic risk factors have been identified for cognitive impairment in PD, including GBA (glucosylceremidase), MAPT (microtubule-associated protein tau), APOE (apolipoprotein E), LRRK2 (leucine-rich repeat serine/threonine-protein kinase 2), SNCA (α-synuclein), COMT (catechol-O-methyltransferase), BDNF (brain-derived neurotrophic factor), and various genes involved in inflammation/immune responses, such as IL10 (associated with lower risk of cognitive impairment), IL17A (associated with higher risk of cognitive impairment), IL18, and IFNG [1].