IDH1 Mutation in Cancer
OncogeneIsocitrate Dehydrogenase 1
IDH1 mutations produce the oncometabolite 2-hydroxyglutarate, which alters DNA methylation and blocks cell differentiation. IDH1 mutations define a distinct subtype of glioma and AML with better prognosis.
What Is IDH1?
IDH1 (Isocitrate Dehydrogenase 1) encodes a metabolic enzyme that catalyzes the oxidative decarboxylation of isocitrate to α-ketoglutarate (α-KG) in the cytoplasm. Oncogenic IDH1 mutations are neomorphic — rather than losing enzyme function, the mutant IDH1 gains a new activity: converting α-KG to 2-hydroxyglutarate (2-HG), an oncometabolite. 2-HG accumulation inhibits α-KG-dependent dioxygenases, causing widespread epigenetic dysregulation through DNA and histone hypermethylation.
IDH1 Mutations in Brain Tumors
IDH1 mutations are a defining molecular feature of lower-grade gliomas and secondary glioblastoma. The R132H mutation accounts for over 90% of IDH1 mutations in gliomas. IDH1 mutations are found in approximately 70-80% of grade II-III gliomas (astrocytomas, oligodendrogliomas), ~10% of glioblastomas (mostly secondary), and ~20% of intrahepatic cholangiocarcinomas. They are also present in ~15% of acute myeloid leukemias. The 2021 WHO Classification of CNS tumors uses IDH mutation status as a primary classifier for adult-type diffuse gliomas.
Prognostic and Therapeutic Implications
IDH1 mutation is one of the strongest positive prognostic markers in gliomas. IDH-mutant gliomas have significantly better overall survival compared to IDH-wildtype tumors (median OS ~7 years vs ~1.5 years for glioblastoma). Vorasidenib, an oral dual IDH1/IDH2 inhibitor, was approved in 2024 for IDH-mutant grade 2 gliomas and is the first targeted therapy for these tumors. Ivosidenib is approved for IDH1-mutant cholangiocarcinoma and AML.
Morphological Associations
IDH1-mutant gliomas display distinctive histological features: diffuse infiltrative growth with less necrosis and microvascular proliferation than IDH-wildtype glioblastoma. IDH-mutant astrocytomas show characteristic nuclear atypia patterns, while oligodendrogliomas exhibit the classic "fried egg" morphology. HistoAtlas quantifies these morphological differences across cancer types using computational analysis of H&E-stained whole slide images.
Frequently Asked Questions
What is an IDH1 mutation?
An IDH1 mutation is a change in the IDH1 gene that causes the enzyme to produce an abnormal metabolite called 2-hydroxyglutarate (2-HG), which disrupts normal cell development through epigenetic changes. IDH1 mutations are most common in brain tumors (gliomas), where the R132H mutation defines a distinct disease entity with better prognosis.
What is IDH1 mutation in brain tumors?
IDH1 mutations are found in 70-80% of lower-grade gliomas (grade II-III) and about 10% of glioblastomas. IDH1-mutant brain tumors are a molecularly distinct category in the WHO Classification, with significantly better prognosis than IDH-wildtype tumors. The R132H mutation accounts for over 90% of IDH1 mutations in gliomas.
What is IDH1 mutation treatment?
Vorasidenib, an oral dual IDH1/IDH2 inhibitor, was approved in 2024 for IDH-mutant grade 2 gliomas — the first targeted therapy for these tumors. Ivosidenib is approved for IDH1-mutant cholangiocarcinoma and acute myeloid leukemia. Standard glioma treatments (surgery, radiation, temozolomide) remain the backbone of care.
Does IDH1 mutation affect survival?
Yes — IDH1 mutation is one of the strongest positive prognostic markers in gliomas. IDH-mutant lower-grade gliomas have a median survival of ~7 years, compared to ~1.5 years for IDH-wildtype glioblastoma. HistoAtlas provides survival curves comparing IDH1-mutant vs wild-type tumors across 33 TCGA cancer types.