SYNJ1 and Parkinsonism: Recent studies on inositol investigated the role of SYNJ1, an autosomal recessive form of early-onset parkinsonism.51 SYNJ1 is a lipid phosphatase of phosphatidylinositol-34,5-trisphosphate (PIP3).52 SYNJ1 knockout cell models were associated with an increase of α-synuclein and PIP3 levels.