INPP5E gene encodes a protein named phosphatidylinositol polyphosphate 5-phosphatase type IV, which plays a critical role in phosphoinositide 3-kinase (PI3K) signaling and regulation of protein localization to cilium. Studies also suggest a possible regulatory role in Golgi-vesicular trafficking. Mutations in INPP5E gene result in altered cellular PtdIns ratios and promote premature destabilization of cilial response to stimulation.
Defects in the INPP5E gene cause Joubert syndrome type 1 and mental retardation, truncal obesity, retinal dystrophy, and micropenis syndrome.