Initially, genetic exploration in PD aimed to identify causative genetics or the genetic architecture of the condition, with first discoveries focused on the autosomal dominant and recessive mutations in PD (SCNA, LRRK2, VPS35 and PINK1, DJ-1, Parkin genes) and environment-gene interactions in the pathobiology of PD (Lill, 2016). Here, LRRK2 is linked to Parkinson disease.