Ann Lab Med 2020; 40(1): 72-75
Performance Evaluation of the QXDx BCR-ABL %IS Droplet Digital PCR Assay
Hee-Jung Chung, M.D.1, Mina Hur, M.D., Ph.D.1, Sumi Yoon, M.D.1, Keumrock Hwang, M.D., Ph.D.2*, Hwan-Sub Lim, M.D., Ph.D.2, Hanah Kim, M.D., Ph.D.1, Hee-Won Moon, M.D., Ph.D.1, and Yeo-Min Yun, M.D., Ph.D.1
1Department of Laboratory Medicine, Konkuk University School of Medicine, Seoul, Korea; 2Department of Laboratory Medicine, Seoul Clinical Laboratories, Yongin, Korea
Corresponding author: Mina Hur, M.D., Ph.D.
Department of Laboratory Medicine, Konkuk University School of Medicine, Konkuk University Medical Center, 120-1 Neungdong-ro, Gwangjin-gu, Seoul 05030, Korea
Tel: +82-2-2030-5581 Fax: +82-2-2636-6764 E-mail:

* Current affiliation is Samkwang Medical Laboratories, Seoul, Korea.
Received: July 10, 2019; Revised: August 1, 2019; Accepted: August 16, 2019; Published online: January 1, 2020.
© Korean Society for Laboratory Medicine. All rights reserved.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Accurate detection of BCR-ABL fusion transcripts at and below molecular response (MR) 4 (0.01% International Scale [IS]) is required for disease monitoring in patients with chronic myeloid leukemia (CML). We evaluated the analytical performance of the QXDx BCR-ABL %IS (Bio-Rad, Hercules, CA, USA) droplet digital PCR (ddPCR) assay, which is the first commercially available ddPCR-based in vitro diagnostics product. In precision analysis, the %CV was 9.3% and 3.0%, with mean values of 0.031% IS and 9.4% IS, respectively. The assay was linear in the first order, ranging from 0.032% IS to 20% IS. The manufacturer-claimed limit of blank, limit of detection, and limit of quantification were verified successfully. There was a very strong correlation between the results of the QXDx BCR-ABL %IS ddPCR assay and the ipsogen BCR-ABL1 Mbcr IS-MMR (Qiagen, Hilden, Germany) real-time quantitative PCR assay (r=0.996). In conclusion, the QXDx BCR-ABL %IS ddPCR assay can provide reliable results for CML patients.
Keywords: BCR-ABL, Droplet digital PCR, Performance, Evaluation, Chronic myeloid leukemia

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