Since we did not observe a significant change in the total mass of PI(4,5)P2 in the LS patient NSC, we wondered whether the OCRL enzyme might control a relatively small but functional pool of PI(4,5)P2 at a specific endomembrane in NSC and changes in this small pool might not be reflected in measurements of total PI(4,5)P2 mass measurements. The gene discussed is OCRL; the disease is Leigh syndrome.