<i>IDH1</i> mutation detection by droplet digital PCR in glioma

Abstract

// Jing Wang 1, 2 , Yi-ying Zhao 1 , Jian-feng Li 3 , Cheng-cheng Guo 1 , Fu-rong Chen 1 , Hong-kai Su 1 , Hua-fu Zhao 2 , Ya-kang Long 4 , Jian-yong Shao 4 , Shing-shun Tony To 2 , Zhong-ping Chen 1 1 Department of Neurosurgery/Neuro-oncology, Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China 2 Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China 3 Department of Neurosurgery, Affiliated Shantou Hospital of Sun Yat-Sen University, Shantou, China 4 Department of Molecular Diagnosis, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China Correspondence to: Shing-shun Tony To, e-mail: tony.to@polyu.edu.hk Zhong-ping Chen, e-mail: chenzhp@sysucc.org.cn Keywords: glioma, isocitrate dehydrogenase (IDH), droplet digital PCR (ddPCR), quantitative real-time PCR (qRT-PCR), sensitivity Received: July 27, 2015&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Accepted: October 02, 2015&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Published: October 14, 2015 ABSTRACT Glioma is the most frequent central nervous system tumor in adults. The overall survival of glioma patients is disappointing, mostly due to the poor prognosis of glioblastoma (Grade IV glioma). Isocitrate dehydrogenase (IDH) is a key factor in metabolism and catalyzes the oxidative decarboxylation of isocitrate. Mutations in IDH genes are observed in over 70% of low-grade gliomas and some cases of glioblastoma. As the most frequent mutation, IDH1(R132H) has been served as a predictive marker of glioma patients. The recently developed droplet digital PCR (ddPCR) technique generates a large amount of nanoliter-sized droplets, each of which carries out a PCR reaction on one template. Therefore, ddPCR provides high precision and absolute quantification of the nucleic acid target, with wide applications for both research and clinical diagnosis. In the current study, we collected 62 glioma tissue samples (Grade II to IV) and detected IDH1 mutations by Sanger direct sequencing, ddPCR, and quantitative real-time PCR (qRT-PCR). With the results from Sanger direct sequencing as the standard, the characteristics of ddPCR were compared with qRT-PCR. The data indicated that ddPCR was much more sensitive and much easier to interpret than qRT-PCR. Thus, we demonstrated that ddPCR is a reliable and sensitive method for screening the IDH mutation. Therefore, ddPCR is able to applied clinically in predicting patient prognosis and selecting effective therapeutic strategies. Our data also supported that the prognosis of Grade II and III glioma was better in patients with an IDH mutation than in those without mutation.