In support of this model, abnormal LRRK2 function has been implicated in idiopathic PD (i.e., PD negative for LRRK2 mutations): sensitive proximity ligation assays were used to demonstrate both increased kinase activity and decreased 14-3-3 binding of LRRK2 in substantia nigra neurons from patients with idiopathic PD compared with controls, strengthening the link between abnormalities in LRRK2 function and idiopathic PD (Di Maio et al., 2018). This evidence concerns the gene LRRK2 and Parkinson disease.