Cryptic Insertion of the BCR Gene at 9q34 in Philadelphia-Negative Chronic Myelogenous Leukaemia.
10.15263/jlmqa.2015.37.2.110
- Author:
Hyun Jeong KIM
1
;
Misuk JI
;
Hanah KIM
;
Hee Won MOON
;
Mina HUR
;
Yeo Min YUN
Author Information
1. Department of Laboratory Medicine, Konkuk University School of Medicine, Seoul, Korea. hannasis@kuh.ac.kr
- Publication Type:Case Report
- Keywords:
Chronic myelogenous leukaemia;
Philadelphia-negative;
Cryptic insertion;
Fluorescence in situ hybridisation
- MeSH:
Blood Cell Count;
Bone Marrow;
Chromosomes, Human, Pair 9;
Cytogenetics;
Female;
Humans;
Interphase;
Karyotype;
Leukocytes;
Megakaryocytes;
Metaphase;
Neutrophils;
Polymerase Chain Reaction;
Strikes, Employee;
Young Adult;
Imatinib Mesylate
- From:Journal of Laboratory Medicine and Quality Assurance
2015;37(2):110-114
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
Chronic myelogenous leukaemia (CML) is a myeloproliferative neoplasm that is almost always characterised by the presence of t(9;22)(q34;q11.2). Approximately 5% to 10% of CML patients lack cytogenetic evidence of t(9;22)(q34;q11.2) but have the breakpoint cluster region (BCR)/ABL1 fusion, as revealed by fl uorescence in situ hybridisation (FISH) or the reverse transcription-polymerase chain reaction (RT-PCR). We present a case of Philadelphia-negative CML with a cryptic insertion of BCR at 9q34. A 22-year-old woman incidentally presented with marked leucocytosis and anaemia. Her complete blood count results were as follows: white blood cells, 238.61x10(9)/L; haemoglobin, 9.6 g/dL; platelets, 395x10(9)/L. A peripheral blood smear showed leucocytosis with neutrophilia, basophilia, left-shifted neutrophils, and circulating blasts comprising 2% of the total leucocytes. The bone marrow showed a striking increase in megakaryocytes and granulocytic precursors. The myeloid/erythroid ratio was 7.4:1, and blasts comprised up to 1.8% of all nucleated cells. Bone marrow sections revealed active megakaryopoiesis and granulopoiesis with 100% cellularity. Chromosomal analysis revealed a normal karyotype. However, interphase FISH using a dual-colour BCR/ABL1 fusion probe showed an atypical pattern consisting of one red, two green, and one fusion (1R2G1F) signal in 97.5% of the 200 analysed cells. Metaphase FISH revealed a single BCR/ABL1 fusion signal on chromosome 9. RT-PCR was positive for BCR/ABL1 (b3a2). Quantitative PCR revealed a normalised copy number of 15.32. The patient started her treatment with imatinib, reached a complete molecular response eight months afterwards, and has been coping well without any adverse events.
