It has been demonstrated that mutations in RAB3GAP1 (RAB3 GTPase activating protein catalytic subunit 1), RAB3GAP2 (RAB3 GTPase activating non-catalytic protein subunit 2), and RAB18 (Ras-related protein Rab-18) cause Warburg micro syndrome 1–3 (WARBM1-3). Here, RAB18 is linked to Warburg micro syndrome 1.