A gene that makes a protein called isocitrate dehydrogenase 1 (IDH1). The IDH1 protein helps break down fats for energy and protect cells from harmful molecules. Mutations (changes) in the IDH1 gene have been found in several genetic conditions and in some types of cancer, including acute myelogenous leukemia, myelodysplastic syndromes, and brain cancer. These changes may cause abnormal cells, including cancer cells, to grow and spread in the body. Also called isocitrate dehydrogenase-1 gene.