International Journal of Molecular Sciences Review Minimal Residual Disease Detection in Acute Lymphoblastic Leukemia Aaron Kruse 1, Nour Abdel-Azim 1, Hye Na Kim 1, Yongsheng Ruan 1, Valerie Phan 1, Heather Ogana 1, William Wang 1, Rachel Lee 1, Eun Ji Gang 1, Sajad Khazal 2 and Yong-Mi Kim 1,* 1 Children’s Hospital Los Angeles, University of Southern California, 4650 Sunset Boulevard, MS #57, Los Angeles, CA 90027, USA;
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[email protected] (E.J.G.) 2 Department of Pediatrics Patient Care, Division of Pediatrics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA;
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[email protected] Received: 19 November 2019; Accepted: 3 February 2020; Published: 6 February 2020 Abstract: Minimal residual disease (MRD) refers to a chemotherapy/radiotherapy-surviving leukemia cell population that gives rise to relapse of the disease. The detection of MRD is critical for predicting the outcome and for selecting the intensity of further treatment strategies. The development of various new diagnostic platforms, including next-generation sequencing (NGS), has introduced significant advances in the sensitivity of MRD diagnostics. Here, we review current methods to diagnose MRD through phenotypic marker patterns or differential gene patterns through analysis by flow cytometry (FCM), polymerase chain reaction (PCR), real-time quantitative polymerase chain reaction (RQ-PCR), reverse transcription polymerase chain reaction (RT-PCR) or NGS.