title: BCR/ABL rearrangement with b3a3 fusion transcript in a case of childhood acute lymphoblastic leukemia.
abstract: The role of BCR/ABL isoforms and their relationship to leukemia phenotype have been of major concern. Atypical BCR/ABL mRNA transcripts lacking exon a2 have been reported in 12 cases of acute lymphoblastic leukemia (ALL) to date; among them, a b3a3 type transcript has been reported only once in the childhood ALL. Reported here is the case of a patient with Philadelphia-positive (Ph(+)) ALL expressing a b3a3 type transcript, a rare type of BCR/ABL mRNA lacking ABL exon a2 sequences. Bone marrow showed a hypercellular marrow with leukemic blasts positive for CD10, CD19, CD79a, and cytoplasmic mu, which is consistent with pre-B ALL. The G-banding and fluorescence in situ hybridization analyses indicated Ph(+). After the patient was diagnosed with ALL-L2, induction chemotherapy was performed and imatinib mesylate was thereafter given as the maintenance therapy. Sequencing analysis showed deletion of ABL a2 in the polymerase chain reaction product, which corresponded to a b3a3 fusion transcript. To our knowledge, this is the second report of an aberrant BCR/ABL product lacking ABL exon a2 in childhood ALL.
authors.affiliation: Department of Laboratory Medicine, Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu, Seoul 120-752, Korea.
authors.forename: Juwon
authors.initials: J
authors.lastname: Kim
authors.forename: Tae Sung
authors.initials: TS
authors.lastname: Park
authors.forename: Chuhl Joo
authors.initials: CJ
authors.lastname: Lyu
authors.forename: Jaewoo
authors.initials: J
authors.lastname: Song
authors.forename: Kyung-A
authors.initials: KA
authors.lastname: Lee
authors.forename: Sue Jung
authors.initials: SJ
authors.lastname: Kim
authors.forename: Hyeon-Ji
authors.initials: HJ
authors.lastname: Lee
authors.forename: Jong Rak
authors.initials: JR
authors.lastname: Choi
mesh_terms: D001483:Base Sequence; D002648:Child; D002892:Chromosomes, Human, Pair 22; D002899:Chromosomes, Human, Pair 9; D020732:Cytogenetic Analysis; D004252:DNA Mutational Analysis; D005091:Exons / Q000235:genetics; D016044:Fusion Proteins, bcr-abl / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics* / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D014178:Translocation, Genetic
chemical_list: D020033:Protein Isoforms; D012333:RNA, Messenger; D016044:Fusion Proteins, bcr-abl