Constitutional Chromosome 21 Abnormality in B-ALL with iAMP21 in a Patient Developing Treatment-Related Myelodysplastic Syndrome
10.15264/cpho.2025.32.1.23
- Author:
Inhwa KIM
1
;
Su Hyun YOON
;
Sunghan KANG
;
Kyung-Nam KOH
;
Mi Young KIM
;
Young-Uk CHO
;
Sang-Hyun HWANG
;
Seongsoo JANG
;
Eul-Ju SEO
;
Beom Hee LEE
;
Sunghee MIN
;
Hyunwoo BAE
;
Ho Joon IM
;
Hyery KIM
Author Information
1. Department of Pediatrics, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
- Publication Type:CASE REPORT
- From:Clinical Pediatric Hematology-Oncology
2025;32(1):23-28
- CountryRepublic of Korea
- Language:English
-
Abstract:
The initial molecular cytogenetic characteristics of blasts plays a significant role in determining the treatment course of B-cell acute lymphoblastic leukemia (B-ALL).B-ALL with intrachromosomal amplification of chromosome 21 (iAMP21) has been well known to have unfavorable prognosis. Also, there are previously recognized germline mutations that increase the risk of ALL, such as trisomy 21, Down syndrome. This case report is about a 16-year-old girl who presented with lymphadenitis, purpura, and fever followed by initial lab of elevated white blood cell with blasts.She had some notable facial features, but no typical Down syndrome related one.Bone marrow biopsy and fluorescence in situ hybridization finalized the diagnosis as B-ALL with iAMP21, high-risk group. The minimal residual disease-negative complete remission was achieved after the induction chemotherapy with Korean multicenter high-risk protocol. However, abnormal karyotype was sustained in bone marrow. Microarrays with her buccal swab raised the possibility that the abnormal karyotype was not from the leukemic blasts but rather from the germline. Although she underwent scheduled chemotherapy uneventfully as slow early responder type, thrombocytopenia and abnormal karyotype persisted, leading to the diagnosis of acute myeloid leukemia. Additional chemotherapy and peripheral blood stem cell transplantation was performed which resulted in engraftment. This case highlights the discovery of a constitutional genetic aberration, which played like a silent yet critical background factor for B-ALL with iAMP21. As the number of reported cases are limited, the role of germline chromosome 21 mutation as the indicator for prognosis of B-ALL should be studied further.
