IDH1 and myelodysplastic syndrome: Approximately 50% of d-2-hydroxyglutaric aciduria (d-2-HGA), a rare inherited neurometabolic disorder, has also been found to display IDH1 mutations (14), as well as 10% of intrahepatic cholangiocarcinomas (15), 5% of myelodysplastic syndrome (MDS), 8.8% of myeloproliferative neoplasms (MPN), and fewer than 10% of secondary AML (14).