基于IDH1基因检测联合体外药敏试验的恶性脑胶质瘤个体化综合治疗的疗效评价

目的:研究恶性脑胶质瘤患者异柠檬酸脱氢酶-1（isocitrate dehydrogenase-1，IDH1）突变状态与体外药敏试验结果相关性，以及基于二者的恶性脑胶质瘤患者个体化综合治疗的疗效评价。方法:选择术后病理确诊为恶性脑胶质瘤的患者67例，用Sanger测序法检测IDH1基因突变状态，并取其新鲜标本采用胶滴肿瘤药敏检测技术（CD-DST法）进行体外药敏试验，分析二者之间关联性。根据是否按照体外药敏实验结果进行规范疗程的化疗，将患者分为个体化治疗组和非个体化治疗组，比较两组患者临床疗效。结果:67例患者中，IDH1基因突变者14例，未突变者53例，IDH1基因突变患者卡莫司汀（BCUN）、依托泊苷（VP-16）、替莫唑胺（TMZ）体外药敏试验敏感性高于IDH1野生型患者，差异具有统计学意义（P<0.05）。IDH1基因突变患者中位生存期为30个月，IDH1野生型患者为14个月，差异具有统计学意义（P<0.05）。个体化治疗组患者中位生存时间为22个月，非个体化治疗组患者中位生存时间为14个月，差异具有统计学意义（P<0.05）。IDH1基因突变并行个体化治疗亚组中位生存时间为32个月，明显长于其他亚组，差异具有统计学意义（P<0.05）。结论:IDH1基因检测联合体外药敏试验指导恶性脑胶质瘤患者的个体化综合治疗能获得较好的临床疗效。     

胶质瘤中异柠檬酸脱氢酶的检测及其临床意义

目的 分析异柠檬酸脱氢酶(IDH)在胶质瘤中的突变情况,探讨IDH基因突变对胶质瘤的诊断和预后意义.方法 通过Sanger DNA测序法检测胶质瘤中IDH基因突变情况,同时比较分析IDH突变在不同人群中的突变频率以及对预后的影响.结果 20例胶质瘤患者中发现IDH突变7例,均为IDH1 R132H(C.395G＞ A)突变,突变率为35.0％;存在IDH突变的胶质瘤患者无进展生存期和总生存期优于IDH野生型患者.结论 IDH突变对胶质瘤的辅助诊断和预后判断具有重要的临床意义.     

免疫组织化学法与Sanger测序法对IDH1基因突变检测的比较分析

目的:采用免疫组织化学法(immunohistochemistry,IHC)、Sanger测序法分别对中枢神经系统肿瘤患者异柠檬酸脱氢酶1(isocitrate dehydrogenase 1,IDH1)基因进行突变检测,并对结果的一致性进行分析,为临床IDH1基因突变检测方法的选择提供指导依据。方法:运用IHC和Sanger测序法检测657例人脑胶质瘤及其他中枢神经系统肿瘤中IDH1基因突变。结果:IHC检测结果:657例样本中,230例发生IDH1基因突变,49例组织为少量阳、弱阳等可疑阳性;Sanger测序法检测发现255例存在IDH1基因突变,11例因DNA质量不佳无法获得可评估结果。IHC与Sanger测序法检测IDH1基因突变具有较好的一致性(Kappa=0.88),差异无统计学意义(P=0.49);IDH1基因突变主要发生在WHOⅡ~Ⅲ级的星形细胞瘤、少突胶质细胞瘤、间变星形细胞瘤、间变少突胶质细胞瘤以及WHOⅣ级的继发性胶质母细胞瘤中。结论:IHC检测IDH1基因突变的结果与Sanger测序法检测结果具有较好的一致性,IHC敏感性低于Sanger测序法,但特异性较高,且操作相对简单,适于临床普遍开展和推广;Sanger测序法敏感性高,可检测未知突变位点,IHC检测突变阴性及不确定的病例应进一步使用Sanger测序法验证。     

DH1基因检测联合CD-DST药敏指导胶质瘤术后辅助化疗的临床应用分析

摘 要：［目的］ 研究胶质瘤中异柠檬酸脱氢酶1（isocitrate dehydrogenases 1,IDH1）突变和胶滴肿瘤药敏检测技术（CD-DST）结果的关联性及指导术后辅助化疗方案的疗效分析。［方法］收集手术切除并经病理证实的高级别脑胶质瘤组织57例,新鲜标本分别对替莫唑胺等5种化疗药物进行CD-DST检测指导治疗方案,同时采用直接测序法检测肿瘤组织中IDH1基因突变情况,分析两者相关性。以CD-DST检测结果为指导治疗患者57例,比较16例行指导规范治疗与未行指导规范治疗患者的生存情况。［结果］ 57例高级别脑胶质瘤患者中IDH1突变13例（22.8%）,IDH1突变患者中位总生存时间显著性优于IDH1未突变患者（12.0个月 vs 7.5个月,P=0.002）。IDH1突变患者的替莫唑胺、Vp-16、卡铂和卡莫司汀的体外敏感率高于无IDH1突变的患者,而顺铂敏感性在有无突变组差异无统计学意义。CD-DST指导的行规范治疗与未行规范治疗患者的中位总生存时间分别为12个月和8个月,差异无统计学意义（P>0.05）。IDH1突变联合CD-DST敏感指导规范治疗患者的中位总生存时间为14个月,显著性优于其他组别(P=0.019)。［结论］ IDH1基因检测联合CD-DST技术对于高级别脑胶质瘤术后辅助化疗方案具有一定的临床指导价值。     

63例高级别胶质瘤中IDH1和TERT突变状态的预后价值

目的:探讨异柠檬酸脱氢酶-1（IDH1）和端粒酶逆转录酶（TERT）启动子突变对高级别胶质瘤患者的预后价值。方法:选取2014年9月至2017年6月于我院行手术切除且术后病理提示为高级别胶质瘤的患者63例（WHO Ⅲ级27例，Ⅳ级36例），完善临床资料、随访资料、分子检测结果。应用Sanger测序法检测样本中IDH1和TERT启动子突变情况，根据结果将患者分为不同亚组，通过比较其生存期的差异，分析基因突变与患者预后的关系。结果:63例高级别胶质瘤中，IDH1突变型和野生型患者的中位生存期分别为24和10个月，差异有统计学意义（P＜0.01）；TERT突变型和野生型的中位生存期无明显差异（P＞0.05）。IDH1突变为高级别胶质瘤患者预后良好的因素，TERT突变不能单独提示预后，二者联合分析提示:IDH1突变／TERT突变组预后最好，IDH1野生／TERT突变组预后最差，IDH1突变／TERT野生组预后稍好于IDH1野生／TERT野生组，四组间预后有明显差异。结论:IDH1突变的高级别胶质瘤患者有较好的临床预后，在此基础上，TERT启动子突变检测有助于进一步划分其预后分层。     

IDH1基因突变在脑胶质瘤中的研究进展

脑胶质瘤是中枢神经系统较常见的肿瘤之一, 尽管目前诊疗技术得到长足的发展, 但疗效仍然不尽如人意。随着分子病理学的发展, 人们越来越关注脑胶质瘤中一些分子水平的异常在诊断和治疗疾病中的意义。近年来研究发现, 脑胶质瘤患者存在高频率的异柠檬酸脱氢酶-1(isocitrate dehydrogenases-1, IDH1)基因突变现象, 而且该突变与脑胶质瘤的诊断分型和临床预后有明确的关系, 对其深入研究, 有望找到脑胶质瘤治疗的新靶点, 对改善当前脑胶质瘤治疗现状有着深远的意义。      

人异柠檬酸脱氢酶1（IDH1）R132 H突变型脑胶质瘤细胞的原代培养及鉴定

目的：建立简单、方便、高效的异柠檬酸脱氢酶1（IDH1）突变型胶质瘤原代细胞体外培养方法,为研究IDH1突变型脑胶质瘤提供细胞模型。方法：样本组织取自低级别脑胶质瘤手术患者,采用组织块法行原代细胞培养,倒置显微镜下观察细胞形态特点;瘤组织应用苏木精－伊红染色法（HE ）和免疫组织化学染色确定胶质瘤病理类型以及级别;原代细胞提取基因组行碱基序列测序以鉴定IDH1突变类型;采用MTT法绘制生长曲线,检测IDH1突变型细胞的体外增殖特性。结果：成功建立WHOⅡ级IDH1 R132H突变型人脑星形胶质细胞瘤细胞株,并可传代。结论：应用合适的方法以及培养液,可以培养出IDH1 R132H突变型人脑胶质瘤原代细胞。     

异柠檬酸脱氢酶基因突变在脑胶质瘤中的研究进展

异柠檬酸脱氢酶1（IDH1）基因突变在神经胶质瘤中的研究备受关注。IDH1突变导致酶原有活性下降,同时获得将α-酮戊二酸转化为2-羟戊二酸的新功能,并改变了胶质瘤的表观遗传学特征,使胶质瘤代谢重编程,破坏胶质瘤氧化还原稳态。本文简述了IDH1突变在胶质瘤中的机制、诊断价值、预后判断和靶向治疗的国内外研究进展,为IDH1突变深入研究、进一步了解胶质瘤病因及干预措施打下基础,亦为胶质瘤分子水平分类和治疗提供新思路。     

DH1基因突变及MGMT基因启动子

摘 要：［目的］ 探讨IDH1基因突变及MGMT基因启动子甲基化状态在指导胶质瘤患者临床化疗和预后判断的意义。［方法］ 运用PCR测序和焦磷酸测序方法对190例胶质瘤患者的肿瘤标本分别进行IDH1基因突变和MGMT基因启动子甲基化状态分析;分析两者与胶质瘤患者临床病理特征及预后的关系。［结果］ 胶质瘤中IDH1基因突变在不同年龄（P=0.026）、病理分级（P=0.020）、KPS评分（P=0.004）组间分布差异有统计学意义;而在不同性别（P=0.900）、p53表达（P=0.878）、肿瘤幕上幕下位置（P=0.106）组间分布差异无统计学意义。MGMT基因启动子甲基化在不同年龄（P=0.488）、性别（P=0.447）、病理分级（P=0.287）、KPS评分（P=0.077）、p53表达（P=0.970）及肿瘤幕上与幕下位置不同（P=0.915）。IDH1基因突变型组与野生型组30个月总生存期差异有统计学意义（P=0.002）,高级别胶质瘤术后化疗患者MGMT基因启动子甲基化组与非甲基化组30个月总生存期差异有统计学意义（P=0.049）。［结论］ IDH1基因突变可作为判断胶质瘤患者预后的指标,而MGMT基因启动子甲基化可作为指导化疗的重要指标。     

IDH1突变在胶质瘤中的研究进展

脑胶质瘤是一种常见的颅内原发恶性肿瘤,起源于神经胶质细胞,严重影响人类的健康。随着神经肿瘤分子的发展,异柠檬酸脱氢酶-1（isocitrate dehydrogenase,IDH1）已经成为目前胶质瘤分子标志物的研究热点。IDH1的突变引起2-羟基戊二酸（2-hydroxyglutaric acid,2-HG）异常增高,进一步导致DNA和组蛋白高甲基化,目前已经成为研究的潜在靶点,这一发现能够使胶质瘤的临床治疗获益。本文概述了突变型IDH1的功能,以及目前IDH1突变在胶质瘤发生机制中的作用。此外,还讨论了IDH1突变的胶质瘤的靶向治疗、免疫治疗及临床预后。     

Detection of IDH1 mutation in human gliomas: comparison of immunohistochemistry and sequencing

Isocitrate dehydrogenase 1 (IDH1) mutations have recently been identified as early and frequent genetic alterations in astrocytomas, oligodendrogliomas, and oligoastrocytomas, as well as secondary glioblastomas, whereas primary glioblastomas very rarely contain IDH1 mutations. Furthermore, a specific monoclonal antibody, IMab-1, which recognizes IDH1-R132H—the most frequent IDH1 mutation—has been generated. IMab-1 has been reported to react with the IDH1-R132H protein, but not the wild-type IDH1 or the other IDH1 mutant proteins in Western-blot analysis. However, the importance of immunohistochemistry using IMab-1 has not yet been elucidated. In this study, we compared the findings from IMab-1 immunohistochemistry and direct DNA sequencing using 49 glioma samples. IMab-1 detected 12 out of 49 cases; however, only nine cases were found to be IDH1-R132H by direct DNA sequencing because of a small population of IDH1-R132H mutation-possessing tumor cells, indicating that IMab-1 immunohistochemistry is useful for detecting IDH1-R132H. We conducted immunohistochemical detection in 52 cases of grade III astrocytomas. The median time to progression (TTP) was significantly longer in the cases with the IDH1 mutation (86.7 months) compared to the cases without the IDH1 mutation (wild type, 10.4 months) (p < 0.01). In conclusion, the anti-IDH1-R132H-specific monoclonal antibody IMab-1 is very useful for detecting IDH1-R132H in immunohistochemistry, and predicting the time to progression in grade III anaplastic astrocytomas. Therefore, IMab-1 is likely to be useful for the diagnosis of mutation-bearing gliomas and for determining the treatment strategy of grade III gliomas.     

Detection of IDH1 Mutation in cfDNA and Tissue of Adult Diffuse Glioma with Allele-Specific qPCR

Background: The World Health Organization (WHO) classification of central nervous system (CNS) tumors necessitates testing of isocitrate dehydrogenase (IDH) 1/2 gene mutation in patients with adult-type diffuse glioma (ADG) for better disease management. In clinical practice, the testing of IDH1 is primarily achieved using immunohistochemistry (IHC) specific to IDH1-R132, which carries a sensitivity of 80% and specificity of 100%. However, in some cases, non-specific background staining or regional heterogeneity in the protein expression of IDH1 may necessitate confirmatory genetic analysis. Robust and reliable assays are needed for IDH1/2 mutation testing. The aim of the current study was to detect IDH1 mutation in cfDNA and tissue of adult-type diffuse glioma with allele-specific qPCR. Materials and Methods: In the current study, IDH1-R132H mutation was analyzed in tumor tissue with paired cell-free DNA (cfDNA) in patients with ADG (n = 45) using IHC and competitive allele-specific Taqman PCR (CAST-PCR). Genomic DNA was extracted from formalin-fixed paraffin-embedded (FFPE) tissue and matched serum for cfDNA using commercially available kits. CAST-PCR with IHC for the detection of IDH1-R132H mutation was also compared. Results: The IDH1-R132H mutation was detected in 46.67% (21/45) cases and 57.78% (26/45) cases using IHC and allele-specific CAST-PCR. In cfDNA of matched IDH1-mutant FFPE tissue DNA, IDH1-R132H mutation was detected in 11.54% (3/26) using CAST-PCR. The concordance rate for IDH1-R132Hmutation between IHC and CAST-PCR was 80.77% (21/26). Conclusion: The CAST-PCR assay is more precise and sensitive for  IDH1-R132Hdetection than traditional IHC, and IDH1-R132H mutation detection using cfDNA may add to the current methods of glioma genomic characterization.     

Comparative study of IDH1 mutations in gliomas by immunohistochemistry and DNA sequencing

Background

Mutations involving isocitrate dehydrogenase 1 (IDH 1) occur in a high proportion of diffuse gliomas, with implications on diagnosis and prognosis. About 90% involve exon 4 at codon 132, replacing amino acid arginine with histidine (R132H). Rarer ones include R132C, R132S, R132G, R132L, R132V, and R132P. Most authors have used DNA-based methods to assess IDH1 status. Preliminary studies comparing imunohistochemistry (IHC) with IDH1-R132H mutation-specific antibodies have shown concordance with DNA sequencing and no cross-reactivity with wild-type IDH1 or other mutant proteins. The present study compares results of IHC with DNA sequencing in diffuse gliomas.

Materials and methods

Fifty diffuse gliomas with frozen tissue samples for DNA sequencing and adequate tissue in paraffin blocks for IHC using IDH1-R132H specific antibody were assessed for IDH1 mutations.

Results

Concordance of findings between IHC and DNA sequencing was noted in 88% (44/50) cases. All 6 cases with discrepancy were immunopositive with DIA-H09 antibody. While in 3 of these 6 cases, DNA sequencing failed to reveal any mutations, R132L (arginine replaced by leucine) mutation was found in the rest 3 cases. Interestingly, of the immunopositive cases, 46.6% (14/30) showed immunostaining in only a fraction of tumor cells.

Conclusions

IHC is an easy and quick method of detecting IDH1-R132H mutations, but there may be some discrepancies between IHC and DNA sequencing. Although there were no false-negative cases, cross-reactivity with IDH1-R132L was seen in 3, a finding not reported thus far. Because of more universal availability of IHC over genetic testing, cross-reactivity and staining heterogeneity may have bearing over its use in detecting IDH1-R132H mutation in gliomas.     

Characterizing invading glioma cells based on IDH1-R132H and Ki-67 immunofluorescence

Glioma, the most common primary brain tumor, is characterized by proliferative-invasive growth. However, the detailed biological characteristics of invading glioma cells remain to be elucidated. A monoclonal antibody (clone HMab-1) that specifically and sensitively recognizes the isocitrate dehydrogenase-1 (IDH1) protein carrying the R132H mutation can identify invading glioma cells by immunostaining. To investigate the degree of invasion in gliomas of distinct grades and the proliferative capacity of the invading cells, immunofluorescent staining was conducted using antibodies against IDH1-R132H and Ki-67 on 11 surgical and autopsy specimens of the tumor core and the invading area. Higher numbers of IDH1-R132H-positive cells in the invading area correlated with a higher tumor grade. Double staining for IDH1-R132H and Ki-67 demonstrated that most invading cells that expressed IDH1-R132H were not stained by the Ki-67 antibody, and the ratio of Ki-67-positive cells among IDH1-R132H-positive cells was significantly lower in the invasion area than in the tumor core in all grades of glioma. These data suggest that higher grade gliomas have a greater invasive potential and that invading cells possess low proliferative capacity.     

Immunohistochemical detection of IDH1 mutation, p53, and internexin as prognostic factors of glial tumors

Isocitrate dehydrogenase 1 (IDH1) mutations, which are early and frequent genetic alterations in astrocytomas, oligodendrogliomas, oligoastrocytomas, and secondary glioblastomas, are specific to arginine 132 (R132). Recently, we established monoclonal antibodies (mAbs) against IDH1 mutations: anti-IDH1-R132H and anti-IDH1-R132S. However, the importance of immunohistochemistry using the combination of those mAbs has not been elucidated. For this study, 164 cases of glioma were evaluated immunohistochemically for IDH1 mutations (R132H and R132S) using anti-IDH1 mAbs (HMab-1 and SMab-1). IDH1 mutation was detected, respectively, in 9.7%, 63.6%, 51.7%, and 77.8% of primary grade IV, secondary grade IV, grade III, and grade II gliomas. For each grade of glioma, prognostic factors for progression-free survival and overall survival were evaluated using clinical and pathological parameters in addition to IDH1 immunohistochemistry. IDH1 mutation, p53 overexpression, and internexin expression, as evaluated using immunohistochemistry with clinical parameters such as degree of surgical removal and preoperative Karnofsky Performance Status (KPS), might be of greater prognostic significance than histological grading alone in grade III as well as IDH1 mutation in grade IV gliomas.     

Comparison of immunohistochemistry, DNA sequencing and allele-specific PCR for the detection of IDH1 mutations in gliomas

Previous studies have identified mutations of the isocitrate dehydrogenase 1 (IDH1) gene in more than 70% of World Health Organization (WHO) grade II and III gliomas. The most frequent mutation leads to a specific amino acid change from arginine to histidine at codon 132 (c.395G>A, p.R132H). IDH1 mutated tumors have a better prognosis than IDH1 non-mutated tumors. The aim of our study was to evaluate and compare the methods of mIDH1 R132H immunohistochemistry, allele-specific PCR and DNA sequencing for determination of IDH1 status. We performed a retrospective study of 91 patients with WHO grade II (n=43) and III (n=48) oligodendrogliomas. A fragment of exon 4 spanning the sequence encoding the catalytic domain of IDH1, including codon 132, was amplified and sequenced using standard conditions. Allele-specific amplification was performed using two forward primers with variations in their 3' nucleotides such that each was specific for the wild-type or the mutated variant, and one reverse primer. Immunohistochemistry was performed with mouse monoclonal mIDH1 R132H. DNA was extracted from FFPE sections following macrodissection. IDH1 mutations were found in 55/90 patients (61.1%) by direct sequencing. R132H mutations were found in 47/55 patients (85.4%). The results of the allele-specific PCR positively correlated with those from DNA sequencing. Other mutations (p.R132C, p.R132S and pR132G) were found by DNA sequencing in 3, 3 and 2 tumors, respectively (8/55 patients, 14.6%). mIDH1 R132H immunostaining was found in the 47 patients presenting the R132H mutation (sensitivity 47/47, 100% for this mutation). None of the tumors presenting a wild-type IDH1 gene were stained (specificity 35/35, 100%). Our results demonstrate that immunohistochemistry using the mIDH1 R132H antibody and allele-specific amplification are highly sensitive techniques to detect the most frequent mutation of the IDH1 gene.     

Comparison of Polymerase Chain Reaction–Restriction Fragment Length Polymorphism,Immunohistochemistry, and DNA Sequencing for the Detection of IDH1 Mutations in Gliomas

Background: IDH1 mutation shows diagnostic, prognostic, and predictive value in gliomas. Direct Sanger sequencing is considered the gold standard to detect IDH1 mutation. However, this technology is not available in most neuropathological centers in developing countries such as Indonesia. Immunohistochemistry (IHC) and polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) have also been used to detect IDH1 mutation. This study aimed to compare DNA sequencing, IHC, and PCR–RFLP in detecting IDH1 mutations in gliomas. Methods: Research subjects were recruited from Dr. Sardjito Hospital. Genomic DNA was extracted from fresh or formalin-fixed paraffin-embedded samples of tumor tissue. DNA sequencing, PCR–RFLP and IHC were performed to detect IDH1 mutation. Sensitivity, specificity, and accuracy of PCR–RFLP and IHC were calculated by comparing them to DNA sequencing as the gold standard. Results: Among 61 recruited patients, 13 (21.3%) of them carried a mutation in codon 132 of the IDH1 gene, as shown by DNA sequencing. PCR–RFLP and DNA sequencing have a concordance value of 100%. Meanwhile, the concordance value between IDH1 R132H IHC and DNA sequencing was 96.7%. The sensitivity, specificity, positive predictive values, negative predictive values, and accuracy for PCR–RFLP were all 100%. On the other hand, the sensitivity, specificity, and accuracy of IHC were 92.3%, 97.9%, and 96.7%, respectively. Conclusion: This study showed that both PCR–RFLP and IHC have high accuracy in detecting IDH1 mutation. We recommend a combination of PCR–RFLP and IHC to detect IDH1 mutation in resource-limited settings.     

不同病理级别胶质瘤细胞中IDH1基因变异表达观察

背景与目的:胶质瘤是最常见的成人原发性神经系统恶性肿瘤,具有较高的病死率和病残率。深入研究胶质瘤的发生发展,无论对于其诊断还是治疗,都具有重要意义。本文通过观察异柠檬酸脱氢酶1(IDH1)基因变异在不同病理级别胶质瘤中表达,初步分析IDH1基因变异与胶质瘤病理分级的相关性及意义。方法:采用直接测序法对30例不同病理级别胶质瘤标本进行IDH1基因变异检测,并取5例外伤额颞叶减压脑组织标本作为对照。比色法计算肿瘤组织内IDH1酶活力,结果采用SPSS13.0进行统计学分析。结果:30例胶质瘤标本中16例(53.33%)发生IDH1基因变异,并与肿瘤病理分级具有相关性,变异后酶活力下降明显。结论:IDH1基因变异在胶质瘤中发生频率较高,变异后酶活力下降,将影响胶质瘤的发生发展。     

Interlaboratory comparison of IDH mutation detection

Isocitrate dehydrogenase (IDH) mutational testing is becoming increasingly important. For this, robust and reliable assays are needed. We tested the variation of results between six laboratories of testing for IDH mutations. Each laboratory received five unstained slides from 31 formalin-fixed paraffin-embedded (FFPE) glioma samples, and followed its own standard IDH diagnostic routine. All laboratories used immunohistochemistry (IHC) with an antibody against the most frequent IDH1 mutation (R132H) as a first step. Three laboratories then sequenced only IHC negative cases while the others sequenced all cases. Based on the overall analysis, 13 samples from 11 tumors had an R132H mutation and one tumor showed an R132G mutation. Results of IHC for IDH1 R132H mutations in all six laboratories were completely in agreement, and identified all R132H mutations. Upon sequencing the results of two laboratories deviated from those of the others. After a review of the entire diagnostic process, on repeat (blinded) testing one laboratory was completely in agreement with the overall result. A change in technique did only partially improve the results in the other laboratory. IHC for the IDH1 R132H mutation is very reliable and consistent across laboratories. IDH sequencing procedures yielded inconsistent results in 2 out of 6 laboratories. Quality assurance is pivotal before IDH testing is made part of clinical management of patients.