Although the vast majority of patients with sporadic PD display Lewy body pathology autopsy, studies have unexpectedly revealed that Lewy bodies are absent in a significant subset of LRRK2 cases (20 of 37 LRRK2 cases studied and 6 of 17 G2019S PD cases) [107], suggesting that at least in some cases, LRRK2 might drive PD independently from alpha-synuclein or Lewy bodies. This evidence concerns the gene LRRK2 and Parkinson disease.