ITGA8 and Parkinson disease: ITGA8 expressing in brain mediates cell-cell interactions and regulates neurite outgrowth of sensory and motor neurons [8]. ITGA8 gene was firstly shown associated with PD in Caucasian population in Simón-Sánchez's study but failed to replicate in other studies of Greece, Irish, and Polish series [4, 19, 20]. ITGA8 variant rs7077361 showed no evidence of relation to PD in our population.