Mutations in different family members lead to specific and severe developmental disorders such as Lowe syndrome and Dent disease (OCRL), or MORM syndrome and Joubert syndrome (INPP5E) [65], and most recently identified Marinesco–Sjögren Syndrome (MSS) caused by mutations in INPP5K [66,67]. The gene discussed is INPP5K; the disease is Marinesco-Sjögren syndrome.