While the underlying cause of Ollier disease is unknown, and most of the reported cases belong to the pre-molecular era, the current literature postulates that the etiology of Ollier disease is related to an early post-zygotic gain-of-function sporadic and non-heritable mutation in the isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2) [46,47,48,49]. This evidence concerns the gene IDH2 and Ollier disease.