NADPH production, which is vital for protecting cells from oxidative stress, depends on IDH enzyme. If there is any mutation in this enzyme , it will adversely affects the cell. Progretion of tumors and other diseases occurs consecutively.

1. Isocitrate dehydrogenase
mutations in hereditary
diseases
Made by :
Amani Mohe
Amal Ebrahim
Amal Gamal
Amal EL-Sayed
Amal Refaat

2. Isocitrate dehydrogenase (IDH) :
In humans, IDH exists in three isoforms:
IDH1 and IDH2 :
 catalyze the third step of
the citric acid cycle outside the
context of the citric acid cycle.
 use NADP+ as a cofactor
instead of NAD+.
they localize to the cytosol
as well as the mitochondrion .
IDH3:
 catalyzes the third step of
the citric acid cycle
converts NAD+ to NADH
in the mitochondria.

3. Isocitrate dehydrogenase (IDH) is an enzyme that catalyzes the
oxidative decarboxylation of isocitrate, producing α-ketoglutarate
and CO2.

4. IDH function
 The reaction catalyzed by IDH1 and IDH2 is thought to be one of
only three major mechanisms of NADPH production in mammalian
cells.
NADPH is the major carrier of reducing equivalents in cells.
Therefore, mutations that disrupt the normal functions of IDH1 and
IDH2 may have significant consequences for cellular redox balance.

5. IDH mutation
The mutant IDH enzymes acquire an altered activity in which the
normal product α-KG is converted to 2-hydroxyglutarate (2-HG).
The product of the novel reaction, 2-HG, is a poorly understood
metabolite that does not participate in any known productive metabolic
pathway.

6. Role of mutated IDH in tumors
Production of 2HG by the mutant enzyme is responsible for driving
tumor progression. Hence, 2HG has been described as an
“oncometabolite”.
IDH mutations are not a common event in
primary glioblastoma (5% to 15%) .
IDH mutations occur early during
gliomagenesis .
(1) Glioma

7. (2) AML
(3) ALTL
(Acute myeloid leukemia)
Approximately half of all such mutations
occur in IDH2 .
AITL is peripheral T-cell lymphoma .
IDH2 mutations are present in approximately 20% to
45% of AITL cases.
IDH1 mutations have not been detected in patients
with AITL

8. (4)
Chondrosarcoma
Approximately 50% of chondrosarcomas
were found to have IDH1 or IDH2 mutations,
with IDH1 mutations predominating.
(5)
Cholangiocarcinoma
Cholangiocarcinomas are a relatively rare
subset of gastrointestinal malignancies involving
the gall bladder and bile duct.
IDH1 mutations were more common
than IDH2 mutations.

9. 2HG
Acidurias
There is another clinical situation that results in high levels
of 2-HG.
A group of rare, inherited, neurometabolic disorders
characterized by dramatically elevated 2HG levels in the
central nervous system (CNS), serum, and urine .
Half of 2HG acidurias, are caused by loss-of-function
mutations in the 2-HG dehydrogenase enzymes responsible
for converting 2HG back into α-KG.

10. Reference
Oncogenic Isocitrate Dehydrogenase Mutations: Mechanisms,
Models, and Clinical Opportunities.
Rob A. Cairns and Tak W. Mak .
Cancer Discovery July 2013.
Thank you