Clinically, among the multisystem disorders, Warburg Micro syndrome (WMS) ([96,97] for review of clinical and genetic heterogeneity) shares a number of features with Vici syndrome, in particular severe mental retardation, corpus callosum hypoplasia, (acquired) microcephaly, congenital cataracts, optic atrophy and seizures, a phenotypical overlap likely to be explained by the recently described close molecular links between EPG5 and RAB3GAP1 [98], one of the causative proteins implicated in this genetically heterogeneous condition. This evidence concerns the gene RAB3GAP1 and Vici syndrome.