IDH2 and infantile convulsions and choreoathetosis: Other studies have confirmed the frequent occurrence in iCCAs of inactivating mutations in various chromatin-remodeling genes (including BAP1, ARID1A and PBRM1): a mutation of one of these genes occurs almost in half of iCCA patients; in addition, mutations of the IDH1 and IDH2 genes were observed in about 20% of iCCA patients and their presence was associated with negative prognosis [33].