Cytogenetic pattern of childhood leukemia in Taiwan

Background: Cytogenetic analyses of leukemic cells can be used to define specific subgroups of leukemia with different prognoses and, thereby, indicate appropriate treatment for individual cases. In this study, we investigated the cytogenetic pattern of childhood leukemia in Taiwanese patients. Methods: A modified trypsin method of Seabright was used for G-banding of metaphase cells. Results: From October 1996 to January 1999, 111 children with a diagnosis of leukemia were enrolled in the study. Of these, 73 patients had a diagnosis of acute lymphoblastic leukemia (ALL) and 63 of these patients had successful karyotyping of their leukemic cells. Among them, 20 (30.3%) had a normal karyotype, five had hypodiploidy (all had 45 chromosomes), five had low hyperdiploidy (47-50 chromosomes), 16 (24.2%) had high hyperdiploidy (> 50 chromosomes), and 20 had pseudodiploidy. Chromosomal translocation was identified in 24 (36.4%) of the ALL patients, 17 of whom had recurrent translocations including 10 with CD10⁺ B-precursor ALL [4 with t(9;22), 5 with t(1;19), and 1 infant with t(8;14) (q24;q11)], one neonate with CD10^- early pre-B ALL with t(4;11), three B-cell cases with t(8;14), and three T-cell cases [2 with t(11;19) (q23;p13), and 1 (11;14) (p13;q11)]. One B-precursor patient had dic(9;12). Karyotypes of the 30 patients with acute myeloid leukemia (AML) included eight with t(8;21); seven with the French-American-British-M2 subtype (FAB-M2) and one with M1. All four of the patients with M3 had t(15;17), one patient with M4 had inv(16) and 7q-, one with M4Eo (M4 with eosinophilia) had t(7;16) (q21;q22), one with M0 had t(4;11) (q21;q23), and the remaining 11 had a normal karyotype. Three of the five adult-type chronic myeloid leukemia patients had standard Philadelphia chromosome, and the other two had a variant-form of Philadelphia chromosome. Both of the patients with juvenile myelomonocytic leukemia and one patient with myelodysplastic syndrome had a normal karyotype. Conclusions: Most findings were similar to previous reports. Although the high proportion of FAB-M2 patients (7/8) with t(8;21) and the consequently higher frequency (26.7%) of this translocation in the 30 AML cases in this study might have significance, a larger series of cases is needed to establish this finding.