Mutations in Synaptojanin-1 (SynJ1), a PIP-phosphatase enriched in the brain, either in its Sac domain (R258Q and R459P), which dephosphorylates PI4P and PI3P to PI, or in the 5-phosphatase domain (Y832C), which dephosphorylates PI(4,5)P2 to PI4P, have been associated with early onset and typical PD (71, 72, 73, 74). The gene discussed is SYNJ1; the disease is Parkinson disease.