GBA1 and Parkinson disease: Given the role of lipids in PD pathogenesis and the possible influence of LRRK2 and GBA in that relationship, the present study is aimed at determining whether there are differences in the serum lipid profile between sporadic PD (sPD) and the main monogenic causes of familial PD (GBA-associated PD, GBA-PD and LRRK2-associated PD, LRRK2-PD).