The inositol 5-phosphatases oculocerebrorenal syndrome of Lowe (OCRL) and type II inositol polyphosphate 5-phosphatase B (INPP5B) preferentially hydrolyze PI(4,5)P2 to produce phosphatidylinositol 4-phosphate (PI4P; Jefferson and Majerus, 1995; Zhang et al., 1995), although they are also capable of hydrolyzing inositol phosphates Ins(1,4,5)P3 and Ins(1,3,4,5)P4 as well as the inositol lipid PI(3,4,5)P3 (Schmid et al., 2004), at least in vitro. This evidence concerns the gene OCRL and oculocerebrorenal syndrome.