It is clear that there is little consensus among the experts about the causes of PD, which include αSyn alone or in combination with a long list of other factors such as mitochondrial dysfunction, increased leucine-rich repeat kinase 2 (LRRK2, PARK8, and dardarin) activity, exposure to toxins and various combinations of biological, environmental, genetic, gut microbiome, and social factors, among others [116]. Here, LRRK2 is linked to Parkinson disease.