J Neuropathol Exp Neurol
Copyright Ó 2009 by the American Association of Neuropathologists, Inc.
Vol. 68, No. 12
December 2009
pp. 1319Y1325
ORIGINAL ARTICLE
Diagnostic Use of IDH1/2 Mutation Analysis in Routine Clinical
Testing of Formalin-Fixed, Paraffin-Embedded Glioma Tissues
Craig Horbinski, MD, PhD, Julia Kofler, MD, Lindsey M. Kelly,
Geoffrey H. Murdoch, MD, PhD, and Marina N. Nikiforova, MD
Abstract
Mutations in isocitrate dehydrogenase enzyme isoforms 1 (IDH1)
and 2 (IDH2) have been identified in many adult astrocytomas and
oligodendrogliomas. These mutations are targeted to specific codons
(e.g. R132 in IDH1 and R172 in IDH2), making assays to detect
them in clinical specimens feasible. We describe a simple and accurate molecular assay for detection of IDH1/2 mutations on routine
formalin-fixed paraffin-embedded tissues. Using this polymerase
chain reactionYbased assay, we tested 75 glial neoplasms and 57
nonneoplastic conditions that can mimic gliomas including radiation
changes, viral infections, and infarcts. Of the gliomas, 37 (49%) were
positive for IDH1 or IDH2 mutations; the most common mutation
was IDH1 (97%). Two of 12 gangliogliomas were positive for IDH1
mutation, and both had unfavorable clinical outcomes (p G 0.03).
None of the nonneoplastic cases were positive for IDH mutations.
The assay detected IDH mutations in biopsy material containing
mostly glioma and in concomitant near-miss stereotactic core biopsies
that were otherwise equivocal for the presence of glioma by light
microscopy. These results indicate that testing for IDH1/2 mutations
can be effectively performed in a clinical setting and can enhance the
accuracy of diagnosis of gliomas when traditional diagnostic methods
are not definitive.
Key Words: Ganglioglioma, Glioma, Isocitrate dehydrogenase,
Molecular genetics, Paraffin sections, Pediatric oligodendroglioma,
Stereotactic biopsy.
INTRODUCTION
Mutations of isocitrate dehydrogenase enzyme isoforms
1 (IDH1) and 2 (IDH2) have recently been found in a large
proportion of diffuse astrocytic and oligodendroglial neoplasms (1Y4). Isocitrate dehydrogenase enzyme isoform 1 and
IDH2 catalyze the conversion of isocitrate to >-ketoglutarate
while reducing nicotinamide adenine dinucleotide phosphate
(NADP+). Isocitrate dehydrogenase enzyme isoform 1 is located in peroxisomes, whereas IDH2 is present in mitochondria (5). Approximately 90% of IDH1 mutations occur in exon
From the Department of Pathology, University of Kentucky, Kentucky (CH);
and Department of Pathology, University of Pittsburgh, Pittsburgh,
Pennsylvania (JK, LMK, GHM, MNN).
Send correspondence and reprint requests to: Marina N. Nikiforova, MD,
C601, 200 Lothrop St, Pittsburgh, PA 15213; E-mail: nikiforovamn@
upmc.edu
Craig Horbinski was supported by a Callie Rohr American Brain Tumor
Association Fellowship.
Online-only color figures are available at http://www.jneuropath.com.
4 at codon 132, where a CGTYCAT transition changes a
single amino acid from arginine to histidine (R132H). Other
transitions and transversions have been found but, so far, are
restricted to codon 132, which is in the isocitrate-binding
pocket of IDH1. Although the mutation is always heterozygous, it exerts a dominant negative inhibition of IDH1 dimer
activity (6). Less common IDH2 mutations occur in an
analogous codon at position R172 (4). It is not clear whether
depletion of >-ketoglutarate or NADPH reducing equivalents
fully explains the actions of these apparently pro-oncogenic
mutants.
Despite the unresolved mechanism of IDH1/2 mutation
effects, they have been shown to be specific for gliomas compared with non-CNS neoplasms (2, 4); rarely, however, carcinomas and leukemias harbor IDH1 mutations (7). In addition,
IDH1/2 mutations may be prognostic factors associated with
longer survival compared with grade-matched gliomas that
do not harbor such alterations (3, 4, 8). These features make
IDH1 and IDH2 attractive targets for ancillary molecular
testing in tissues for both diagnostic and prognostic purposes.
Prior studies describing IDH mutations predominantly
used archival snap-frozen tissue of biopsies. We report a simple and accurate molecular assay for detection of IDH1/2
mutation in routine formalin-fixed paraffin-embedded (FFPE)
sections and demonstrate diagnostic use and reliability of this
assay for clinical assessment of gliomas.
MATERIALS AND METHODS
Study Design and Histological Processing
Formalin-fixed paraffin-embedded tissue from archival
surgical specimens was selected via electronic searching of the
institutional pathology laboratory information system during
the past 5 years, in keeping with University of Pittsburgh
Institutional Review Board policies. We assessed 132 cases including 75 neoplasms and 57 nonneoplastic lesions. All gliomas were re-evaluated to be certain that grading followed
World Health Organization 2007 criteria (9). Blocks that contained adequate tissue were sectioned at a thickness of 5 Km.
Sections were stained with hematoxylin and eosin to confirm
that diagnostic tissue had been retained; adjacent sections were
evaluated with the IDH1/2 mutation assay. All molecular analyses and interpretations were performed blinded to diagnosis.
IDH1/2 Assays
Tumor targets were manually microdissected from 5-Km
unstained histological sections. DNA was isolated from each
J Neuropathol Exp Neurol Volume 68, Number 12, December 2009
1319
Copyright @ 2009 by the American Association of Neuropathologists, Inc. Unauthorized reproduction of this article is prohibited.
J Neuropathol Exp Neurol Volume 68, Number 12, December 2009
Horbinski et al
TABLE 1. IDH Mutations in Formalin-Fixed
Paraffin-Embedded Tumor Biopsy Samples
Neoplasm Type
No. With
No.
IDH1
Examined Mutation
Fibrillary astrocytoma grade 2
Anaplastic astrocytoma grade 3
Glioblastoma grade 4
Oligodendroglioma grade 2
Anaplastic oligodendroglioma
grade 3
Ganglioglioma
Pilocytic astrocytoma grade 1
Pediatric oligodendroglioma
grade 2
Oligoastrocytoma grade 2
Chordoid glioma
Diffuse large B-cell lymphoma
Hemangioblastoma
Hemangiopericytoma
Myxopapillary ependymoma
Total
%
No. With
IDH2
Mutation %
9
9
6
20
9
3
4
1
16
8
33.3
44.4
16.7
80.0
88.9
0
0
0
1
0
0.0
0.0
0.0
5.0
0.0
12
3
1
2
0
1
16.7
0.0
100.0
0
0
0
0.0
0.0
0.0
1
1
1
1
1
1
75
1
0
0
0
0
0
36
100.0
0.0
0.0
0.0
0.0
0.0
48
0
0
0
0
0
0
1
0.0
0.0
0.0
0.0
0.0
0.0
1.3
Cases were selected and analyzed for IDH1 and IDH2 point mutations at codons
132 and 172, respectively. The 2 cases of ganglioglioma with IDH1 mutations both had
atypical aggressive clinical courses; the pediatric oligodendroglioma case was also
positive for IDH1 mutation.
target using the DNeasy Blood and Tissue kit (Qiagen, Valencia, CA), according to the manufacturer’s instructions. The
quantity of isolated DNA was assessed using a NanoDrop
1000 spectrophotometer (Thermo Scientific, Wilmington, DE).
For the detection of IDH mutations, forward and reverse
primers were designed to amplify exon 4 (codon R132) of the
IDH1 gene and exon 4 (codon R172) of the IDH2 gene using
Primer 3 software (http://frodo.wi.mit.edu/primer3/). The IDH1
forward primer (5¶-ACC AAA TGG CAC CAT ACG A-3¶)
and reverse primer (5¶-GCA AAA TCA CAT TAT TGC CAA
C-3¶) generated a 130-bp polymerase chain reaction (PCR)
product; IDH2 forward primer 5¶-GCT GCA GTG GGA CCA
CTA TT-3¶) and reverse primer (5¶-TGT GGC CTT GTA
CTG CAG AG-3¶) generated a 293-bp PCR product. Both
primers were acceptable for amplification of DNA from FFPE
tissue samples.
Polymerase chain reaction amplification was performed
using 5 to 50 ng of DNA, 0.2 Hmol of each primer, and
AmpliTaq Gold PCR Master Mix (Applied Biosystems, Inc,
Foster City, CA). The reaction mixture was subjected to an
initial denaturation of 95-C for 10 minutes, followed by 35
cycles of amplification, consisting of denaturation at 95-C for
30 seconds, annealing at 55-C for 30 seconds, and extension
72-C for 60 seconds in a total volume of 50 KL. The PCR
products were purified using the MinElute PCR Purification
kit (Qiagen). The PCR products were then sequenced in both
sense and antisense directions with the primers listed above
using the BigDye Terminator v3.1 Cycle Sequencing kit
(Applied Biosystems).
The sequencing reaction mixture was subjected to 25
cycles of amplification consisting of denaturation at 95-C for
1320
30 seconds, annealing at 55-C for 15 seconds, and extension at
60-C for 4 minutes in a total volume of 20 KL. The sequencing products were then purified using Centri-Sep spin columns
(Princeton Separations, Freehold, NJ) and analyzed by capillary gel electrophoresis on ABI3130 (Applied Biosystems).
The Mutation Surveyor software (SoftGenetics, LLC, State
College, PA) was used to assist with the interpretation of the
sequence electropherograms. Each case was classified as positive or negative for the IDH mutation based on the sequencing
results.
Each specimen was evaluated for numbers of viable
and atypical cells. The sensitivity of detection with this assay
was found to be approximately 100 viable nuclei in a microdissected specimen and at least 20% IDH mutant alleles in a
background of normal alleles. The testing was not conducted
when the specimen did not meet these test requirements.
Statistical Analysis
The impact of IDH1 status on risk of progression in
gangliogliomas was determined with a contingency table and
Fisher exact test using GraphPad software (La Jolla, CA).
Results were considered significant when the 2-sided value of
p G 0.05.
RESULTS
A total of 132 FFPE specimens, including 75 neoplasms and 57 nonneoplastic conditions, were analyzed for
the presence of IDH1 and IDH2 mutations (Tables 1 and 2).
Mutations were found in 37 (49%) of the tumors, all of which
were gliomas; no mutation was identified in nonneoplastic
lesions. Of the mutations, 97% were in the IDH1 gene; 1
mutation (3%) was detected in IDH2. Representative positive
mutations on sequencing are shown in Figure 1.
TABLE 2. IDH1 and IDH2 Mutations Are Not Present in
Nonneoplastic Conditions That Mimic Glioma
Nonneoplastic Diagnosis
Ischemia/infarct
Reactive gliosis around
metastatic tumor
Reactive gliosis, idiopathic
Abscess
Vasculopathy/malformation
Viral or Toxoplasma encephalitis
Demyelination
Inflammation NOS
Radiation-induced damage
Vasculitis
PML
Hippocampal sclerosis
Shunt-induced reactive gliosis
Total
No.
Examined
No. With
IDH1
Mutation
No. With
IDH2
Mutation
9
8
0
0
0
0
7
5
5
5
4
4
3
3
2
1
1
57
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Fifty-seven cases representing a variety of nonneoplastic conditions that frequent
mimic gliomas were analyzed for IDH1 and IDH2 point mutations at codons 132 and
172, respectively.
NOS, not otherwise specified; PML, progressive multifocal leukoencephalopathy.
Ó 2009 American Association of Neuropathologists, Inc.
Copyright @ 2009 by the American Association of Neuropathologists, Inc. Unauthorized reproduction of this article is prohibited.
J Neuropathol Exp Neurol Volume 68, Number 12, December 2009
IDH1/2 Assay for Clinical Use
FIGURE 1. IDH1/2 mutations in formalin-fixed paraffin-embedded samples. Unstained slides containing glioma tissue were
sequenced for IDH1 and IDH2 mutations. A total of 85.3% of IDH1-mutated cases had CGTYCAT at codon 132 (R132H). Other
mutations included CGTYTGT (R132C), CGTYAGT (R132S), CGTYCTT (R132L), and CGTYGGT (R132G). Only 1 IDH2
mutation was found, an AGGYATG (R172M).
IDH1/2 Mutations in Glioma Specimens
In the neoplastic cases, 67.3% of the grades 2 and 3
diffuse gliomas were positive for IDH1 mutations and 16.7%
of the glioblastomas were positive. Of all IDH1-positive cases,
85.3% (29/34) were CGTYCAT at codon 132 (R132H). The
remaining cases included 2 CGTYAGT (R132S) in grade 2
and grade 3 oligodendrogliomas; CGTYTGT (R132C) in a
grade 3 oligodendroglioma; CGTYGGT (R132G) in a grade
2 fibrillary astrocytoma; and CGTYCTT (R132L) in a secondary glioblastoma. Only 1 case was positive for an IDH2
mutation, that is, an AGGYATG transversion (R172M) in a
grade 2 oligodendroglioma. No case was positive for both
IDH1 and IDH2 mutations. These results and detection frequencies are in agreement with prior studies (1Y4, 8, 10),
indicating that IDH sequencing reliably detects mutations in
FFPE tissues. In addition, a selection of less common CNS
neoplasms was tested, which included a previously reported
chordoid glioma (11) and a grade 2 pediatric oligodendroglioma. The chordoid glioma was negative for mutations at
both IDH1 and IDH2 codons; the pediatric oligodendroglioma
was positive for the common CGTYCAT transition at codon
132 (R132H) on IDH1 (Table 1).
clinical applications because the demonstration of an IDH
mutation indicates the presence of a glioma and that it cannot
be attributed to nonneoplastic diseases.
IDH Mutations in Suboptimal Tumor Biopsies
To assess whether PCR-based assays can detect IDH
mutations at the outer edge of infiltrating tumors (a common
clinical problem in the evaluation of some stereotactically
obtained biopsies), multipart cases were selected that had
nondiagnostic core biopsies from the periphery of the tumor
in 1 part and a separate part containing unequivocal glioma
that was positive for an IDH mutation. Typically, the diagnostic tissue was obtained by the neurosurgeon after an
intraoperative consultation determined that the initial biopsy
was nondiagnostic. In 3 of 4 cases meeting those criteria a
peripheral biopsy was positive for IDH1 or IDH2 mutation
although the diagnosis on tissue sample was indeterminate by
light microscopic analysis (Fig. 2). In all 3 of these cases, the
mutation exactly matched the central diagnostic tissue result.
One oligodendroglioma had 2 peripheral biopsies, but in only
1 of the 2 was the IDH2 mutation detected (Figs. 2MYR).
These results demonstrate that IDH mutations can be detected
even in equivocal biopsies.
IDH1/2 Mutations in Glioma Nonneoplastic
Conditions That Mimic Glioma
IDH1 Mutations in Gangliogliomas
Although IDH1 and IDH2 mutations have been extensively studied in gliomas, little information is available on the
presence of these mutations in nonneoplastic tissue samples.
Such data are essential before implementation of IDH testing
on a routine clinical basis. Fifty-seven nonneoplastic lesions
were assessed for IDH1 and IDH2, including conditions that
frequently resemble gliomas by light microscopy. None of the
cases, including viral infections, radiation-induced changes,
and reactive gliosis around metastatic tumors, showed IDH1
or IDH2 mutations (Table 2). These results are important for
Included in the neoplastic part of this validation study
were 12 gangliogliomas. Of those cases, 2 were positive for
the CGTYCAT transition at codon 132 (R132H) of the IDH1
gene (Fig. 3). Interestingly, of the 10 gangliogliomas for
which clinical follow-up data were available, only the 2 cases
with IDH1 mutations progressed to high-grade gliomas, each
within a relatively short time (Table 3). These differences in
outcomes were statistically significant (p G 0.03). Of note, the
IDH1-positive ganglioglioma with Batypical features[ (Case 2,
Table 3) showed hypercellularity, nuclear atypia, and a focal
FIGURE 2. IDH mutations are detectable in equivocal formalin-fixed paraffin-embedded samples. Both central CT stereotactic core
biopsies with diagnostic tissue (‘‘central bx’’) and equivocal biopsies of tumor periphery (‘‘peripheral bx’’) were assayed for IDH1
and IDH2 mutations. Case 1 is a gemistocytic astrocytoma (AYF), Case 2 is a grade 3 anaplastic astrocytoma (GYL), and Case 3 is
a grade 2 oligodendroglioma (MYR). In each case, the peripheral biopsy showed reactive changes and hypercellularity suspicious
for glioma but were nondiagnostic and not representative of the tumor ([D] and [E], [J] and [K], [P] and [Q]). The indeterminate
tissue from Cases 1 and 2 revealed IDH1 mutations identical to their corresponding central biopsies ([C] and [F], [I] and [L]). The
IDH2 mutation in Case 3 diagnostic tissue (O) was also identified in the peripheral tissue (R).
Ó 2009 American Association of Neuropathologists, Inc.
1321
Copyright @ 2009 by the American Association of Neuropathologists, Inc. Unauthorized reproduction of this article is prohibited.
Horbinski et al
1322
J Neuropathol Exp Neurol Volume 68, Number 12, December 2009
Ó 2009 American Association of Neuropathologists, Inc.
Copyright @ 2009 by the American Association of Neuropathologists, Inc. Unauthorized reproduction of this article is prohibited.
J Neuropathol Exp Neurol Volume 68, Number 12, December 2009
Ó 2009 American Association of Neuropathologists, Inc.
IDH1/2 Assay for Clinical Use
1323
Copyright @ 2009 by the American Association of Neuropathologists, Inc. Unauthorized reproduction of this article is prohibited.
J Neuropathol Exp Neurol Volume 68, Number 12, December 2009
Horbinski et al
TABLE 3. IDH1 Mutations and Outcomes in Gangliogliomas
Case
Age,
Years
Sex
Location
Radiation
Therapy
IDH1
Status
Follow-Up Interval,
Years
1
2
11
51
F
F
Right temporal
Left parietal
No
Yes
Negative
Positive
4
4
3
10
M
Right temporal
No
Negative
5
4
5
6
7
8
9
10
11
12
1
12
45
8
16
31
15
16
52
M
M
M
M
M
M
F
M
M
Right parietal
Bifrontal
Left frontal
Left temporal
Right parietal
Left frontal
Left occipital
Right frontal
Cerebellum
No
No
Yes
No
No
NA
No
Yes
NA
Negative
Negative
Positive
Negative
Negative
Negative
Negative
Negative
Negative
3
5
4
4
3
NA
5
2
NA
Outcome
No evidence of recurrence
Prior resection was ganglioglioma with Batypical
features[; progressed to glioblastoma in 4 years
Recurrent ganglioglioma 3 years later; no other
recurrence thereafter
No evidence of recurrence
No evidence of recurrence
Progressed to anaplastic oligodendroglioma in 2 years
Small increase in size of residual tumor
No evidence of recurrence
NA
No evidence of recurrence
No evidence of recurrence
NA
Twelve cases of ganglioglioma were tested for IDH1 and IDH2 mutations. Both tumors with IDH1 mutations (Cases 2 and 6) showed high-grade progression within 2 to 4 years;
none of the IDH1-negative tumors with available outcome data showed progression. No ganglioglioma was positive for an IDH2 mutation.
F, female; M, male; NA, not available.
Ki67 proliferation index of up to 10%. Postoperative radiotherapy was initiated when the tumor showed radiological
progression. The other IDH1-positive ganglioglioma (Case 6,
Table 3) had 1p19q codeletion, 1% Ki67 proliferation index,
and a history of low-grade glioma (not otherwise specified)
from an outside institution; adjuvant radiotherapy had been
given 8 years before the ganglioglioma diagnosis was made on
a resection. The original tissue was not available for analysis.
DISCUSSION
We describe a novel diagnostic assay for detection of
IDH1 and IDH2 mutations present in a large proportion of
diffuse gliomas and demonstrate the feasibility and diagnostic
use of IDH testing for clinical assessment of gliomas in
routine FFPE biopsies. This assay accurately detects mutations and does not generate false-positive results in samples
of nonneoplastic conditions that may mimic gliomas. Moreover, this test allows for detection of the mutations even in
biopsies that are equivocal on histological evaluation.
The definitive identification of a biopsy sample as neoplastic is one of the key tasks for pathologists. Nowhere is this
more apparent than in the practice of neuropathology, in which
the diagnosis of an infiltrating glioma may trigger a series of
treatments such as radiation therapy, which can result in permanent damage to the CNS. The difficulty of such diagnoses is
increased by the need for small tissue biopsies of brain and
spinal cord. Therefore, ancillary tests are useful in cases where
the definitive diagnosis cannot be rendered on the basis of
examination by light microscopy alone. Unfortunately for gliomas, the testing for markers such as Ki67 proliferation index,
p53 expression, EGFR amplification, and 1p19q codeletion
has limitations and, with the exception of EGFR amplification
by fluorescence in situ hybridization, is usually unhelpful
when dealing with biopsy samples peripheral to the tumor
centers. TP53 mutations are seen in most diffuse low-grade
gliomas but are scattered over multiple exons, making routine
sequencing impractical.
The recent discovery of IDH1/2 mutations was a major
step forward in neuro-oncology research. Not only is there
only 1 codon per gene to assess, but multiple studies on
multiple continents have found highly concordant results
(1Y4, 10). Furthermore, these mutations are mostly found in
the sorts of cases that are diagnostically most often problematic (i.e. low-grade diffuse gliomas), particularly when the
biopsy sample is from the periphery of a tumor. In many such
cases, the assay will only be able to deliver a diagnosis of
Bglioma,[ but recent work has suggested that certain IDH1
mutations (e.g. R132C) indicate astrocytic differentiation,
whereas IDH2 mutations are more commonly found in oligodendrogliomas (10) (Figs. 2MYR). In some instances, the
glioma diagnosis might not only be proven but also whether
the tumor is more likely astrocytic or oligodendroglial.
Despite the advantages of this novel IDH assay, there
are certain limitations. Even a peripheral biopsy requires a
certain density of glioma cells in the core; for example, this
method requires at least 30% to 40% glioma cells for consistently reliable results (see Materials and Methods section).
Even if there is adequate sampling of glioma nuclei for the
FIGURE 3. Gangliogliomas with IDH mutations may demonstrate atypically aggressive clinical courses. None of the
gangliogliomas with follow-up data (Table 3) that were negative for IDH1 underwent anaplastic transformation. (AYC) A
representative example of a mutation-negative ganglioglioma. (DYO) Both tumors that were IDH1 positive had aggressive courses
(Case 2 [DYI] and Case 6 [JYO]) (Table 3). Arrow in (B) highlights a binucleate cell; arrowheads in (G) and (M) highlight
microvascular proliferation; arrowhead in (N) identifies a mitotic figure.
1324
Ó 2009 American Association of Neuropathologists, Inc.
Copyright @ 2009 by the American Association of Neuropathologists, Inc. Unauthorized reproduction of this article is prohibited.
J Neuropathol Exp Neurol Volume 68, Number 12, December 2009
assay, IDH screening alone would miss the 15% to 30% of
grades 2 and 3 diffuse gliomas and secondary glioblastomas
that are intrinsically negative. Furthermore, primary glioblastomas (the most common gliomas in the adult population)
almost by definition are negative for IDH mutations. Fortunately, the latter group of cases frequently has EGFR amplification, which via fluorescence in situ hybridization can be
detected in a few infiltrating cells on a glass slide. Thus, the
combination of IDH and EGFR ancillary testing could identify
a large proportion of diffuse gliomas of all grades, even with
suboptimal tumor sampling. Nevertheless, because negative
results do not exclude the diagnosis of glioma, this assay
should be used only as an ancillary test and not as a substitute
for analysis by light microscopy.
The IDH mutation screening has been shown to assist
in differentiating between pilocytic and diffuse astrocytomas
(12), and was recently described in gangliogliomas. Consistent
with their World Health Organization grade 1 status, ganglioglioma patient survival after surgery is high and malignant
progression is uncommon (13); there may, however, be a link
between adjuvant radiation therapy and malignant transformation (14, 15). Nevertheless, in this small cohort, the only
gangliogliomas with high-grade transformation and poor
outcomes were those that harbored IDH1 mutations before
progression (Table 3, Fig. 3). This raises the possibility that
such tumors may be variants of ganglioglioma or perhaps are
better classified as diffuse gliomas of either astrocytic or
oligodendroglial lineage (e.g. Case 6 in Table 3, Figs. 3JYO).
A larger study specifically addressing this question will be
necessary to validate and extend these observations.
In summary, detection of IDH1/2 mutations is feasible,
sufficiently robust on FFPE tissue samples, and can be implemented for routine clinical use. It provides additional diagnostic and prognostic information, particularly on small
surgical biopsies. It also may reduce the need for additional
surgeries and provide important information in cases with
equivocal histological features.
Ó 2009 American Association of Neuropathologists, Inc.
IDH1/2 Assay for Clinical Use
ACKNOWLEDGMENT
The authors thank Colleen Lovell for her histological work.
REFERENCES
1. Balss J, Meyer J, Mueller W, et al. Analysis of the IDH1 codon 132
mutation in brain tumors. Acta Neuropathol 2008;116:597Y602
2. Bleeker FE, Lamba S, Leenstra S, et al. IDH1 mutations at residue
p.R132 (IDH1(R132)) occur frequently in high-grade gliomas but not in
other solid tumors. Hum Mutat 2009;30:7Y11
3. Parsons DW, Jones S, Zhang X, et al. An integrated genomic analysis of
human glioblastoma multiforme. Science 2008;321:1807Y12
4. Yan H, Parsons DW, Jin G, et al. IDH1 and IDH2 mutations in gliomas.
N Engl J Med 2009;360:765Y73
5. Thompson CB. Metabolic enzymes as oncogenes or tumor suppressors.
N Engl J Med 2009;360:813Y15
6. Zhao S, Lin Y, Xu W, et al. Glioma-derived mutations in IDH1
dominantly inhibit IDH1 catalytic activity and induce HIF-1alpha.
Science 2009;324:261Y65
7. Kang MR, Kim MS, Oh JE, et al. Mutational analysis of IDH1 codon 132 in
glioblastomas and other common cancers. Int J Cancer 2009;125:353Y55
8. Sanson M, Marie Y, Paris S, et al. Isocitrate dehydrogenase 1 codon 132
mutation is an important prognostic biomarker in gliomas. J Clin Oncol
2009;27:4150Y54
9. Louis DN, Ohgaki H, Wiestler OD, et al. WHO Classification of Tumors
of the Central Nervous System. 4th ed. Lyon, France: IARC; 2007
10. Hartmann C, Meyer J, Balss J, et al. Type and frequency of IDH1 and
IDH2 mutations are related to astrocytic and oligodendroglial differentiation and age: A study of 1,010 diffuse gliomas. Acta Neuropathol
2009;118:469Y74
11. Horbinski C, Dacic S, McLendon RE, et al. Chordoid glioma: A case
report and molecular characterization of five cases. Brain Pathol 2009;
19:439Y48
12. Korshunov A, Meyer J, Capper D, et al. Combined molecular analysis of
BRAF and IDH1 distinguishes pilocytic astrocytoma from diffuse
astrocytoma. Acta Neuropathol 2009;118:401Y5
13. Im SH, Chung CK, Cho BK, et al. Intracranial ganglioglioma:
Preoperative characteristics and oncologic outcome after surgery. J
Neurooncol 2002;59:173Y83
14. Liauw SL, Byer JE, Yachnis AT, et al. Radiotherapy after subtotally
resected or recurrent ganglioglioma. Int J Radiat Oncol Biol Phys 2007;
67:244Y47
15. Rumana CS, Valadka AB. Radiation therapy and malignant degeneration
of benign supratentorial gangliogliomas. Neurosurgery 1998;42:1038Y43
1325
Copyright @ 2009 by the American Association of Neuropathologists, Inc. Unauthorized reproduction of this article is prohibited.