CHRNA4 and Parkinson disease: Notably, the mutant form of kinase 2 containing a leucine‐rich repeat, the most common genetic determinant of PD, prevents the localization of both the D3R and nAChRs to the neuronal membrane, as well as the formation of the D3R‐nAChR heteromer crucial for neuronal homeostasis and the health of dopaminergic neurons [59].