Blood Res 2017; 52(2): 100-105  https://doi.org/10.5045/br.2017.52.2.100
Intrachromosomal amplification of chromosome 21 in Korean pediatric patients with B-cell precursor acute lymphoblastic leukemia in a single institution
Mina Yang1,#, Eun Sang Yi2,#, Hee Jin Kim1, Keon Hee Yoo2, Hong Hoe Koo2, and Sun-Hee Kim1

1Department of Laboratory Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.

2Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.

Correspondence to: Sun-Hee Kim, M.D., Ph.D. Department of Laboratory Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea. sunnyhk@skku.edu
Received: September 5, 2016; Revised: February 1, 2017; Accepted: March 13, 2017; Published online: June 22, 2017.
© The Korean Journal of Hematology. All rights reserved.

Abstract

Background

Intrachromosomal amplification of chromosome 21 (iAMP21), defined as the presence of three or more RUNX1 signals on one marker chromosome, is a distinct cytogenetic subgroup of childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL) that is known to have a poor prognosis when treated with standard therapy. The aim of this study was to evaluate the clinical characteristics of Korean children with iAMP21.

Methods

The cytogenetic data from BCP-ALL children were reviewed. The ETV6/RUNX1 ES Dual Color Probe was used for fluorescence in situ hybridization (FISH).

Results

In total, 295 children were included. Of these, 10 patients (3.4%) had iAMP21. The median age of iAMP21 patients was 9 years, and the median value of white blood cell count was 5.09×109/L. Slow early treatment response was observed more in iAMP21 patients. Patients with iAMP21 had a higher incidence of relapse and worse survival rates. In patients with iAMP21, the estimated 10-year cumulative incidence of relapse was 53.3%. The estimated 10-year event-free survival and overall survival rate were 46.7% and 64.8%, respectively. Most cases of leukemic relapse developed in the late period (median, 43 mo). In multivariate analysis, high risk group was the only factor that had a significant impact on death.

Conclusion

The existence of iAMP21 was related to delayed treatment response and was likely to affect increased relapse and death in the late period. Further studies are needed to reveal its effect on BCP-ALL treatment outcomes and its role as an independent prognostic factor.

Keywords: iAMP21, Childhood BCP-ALL, FISH


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