title: Cytogenetic patterns in ETV6/RUNX1-positive pediatric B-cell precursor acute lymphoblastic leukemia: A Nordic series of 245 cases and review of the literature.
abstract: Between 1992 and 2004, 1,140 children (1 to<15 years) were diagnosed with B-cell precursor acute lymphoblastic leukemia (ALL) in the Nordic countries. Of these, 288 (25%) were positive for t(12;21)(p13;q22) [ETV6/RUNX1]. G-banding analyses were successful in 245 (85%); 43 (15%) were karyotypic failures. The modal chromosome numbers, incidence, types, and numbers of additional abnormalities, genomic imbalances, and chromosomal breakpoints in the 245 karyotypically informative cases, as well as in 152 previously reported cytogenetically characterized t(12;21)-positive ALLs in the same age group, were ascertained. The most common modal numbers among the 397 cases were 46 (67%), 47 (16%), 48 (6%), and 45 (5%). High-hyperdiploidy, triploidy, and tetraploidy were each found in approximately 1%; none had less than 40 chromosomes. Secondary chromosomal abnormalities were identified by chromosome banding in 248 (62%) of the 397 ALLs. Of these, 172 (69%) displayed only unbalanced changes, 14 (6%) only balanced aberrations, and 26 (10%) harbored both unbalanced and balanced abnormalities; 36 (15%) were uninformative because of incomplete karyotypes. The numbers of secondary changes varied between 1 and 19, with a median of 2 additional aberrations per cytogenetically abnormal case. The most frequent genomic imbalances were deletions of 6q21-27 (18%), 8p11-23 (6%), 9p13-24 (7%), 11q23-25 (6%), 12p11-13 (27%), 13q14-34 (7%), loss of the X chromosome (8%), and gains of 10 (9%), 16 (6%), and 21 (29%); no frequent partial gains were noted. The chromosome bands most often involved in structural rearrangements were 3p21 (2%), 5q13 (2%), 6q12 (2%), 6q14 (2%), 6q16 (2%), 6q21 (10%), 6q23 (6%), 6q25 (3%), 9p13 (2%), 11q13 (2%), 11q23 (2%), 12p11 (6%), 12p12 (7%), 12p13 (25%), 21q10 (6%), and 21q22 (6%). Considering that the t(12;21) is known to arise in utero and that the postnatal latency period is protracted, additional mutations are most likely necessary for overt ALL. The frequently rearranged chromosome regions may harbor genes of importance for the transformation and/or progression of an initial preleukemic t(12;21)-positive clone.
authors.affiliation: Pediatrics Unit, Department of Clinical Sciences, University of Umeå, Umeå, Sweden. erik.forestier@pediatri.umu.se
authors.forename: Erik
authors.initials: E
authors.lastname: Forestier
authors.forename: Mette K
authors.initials: MK
authors.lastname: Andersen
authors.forename: Kirsi
authors.initials: K
authors.lastname: Autio
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Blennow
authors.forename: Georg
authors.initials: G
authors.lastname: Borgström
authors.forename: Irina
authors.initials: I
authors.lastname: Golovleva
authors.forename: Sverre
authors.initials: S
authors.lastname: Heim
authors.forename: Kristina
authors.initials: K
authors.lastname: Heinonen
authors.forename: Randi
authors.initials: R
authors.lastname: Hovland
authors.forename: Johann H
authors.initials: JH
authors.lastname: Johannsson
authors.forename: Gitte
authors.initials: G
authors.lastname: Kerndrup
authors.forename: Ann
authors.initials: A
authors.lastname: Nordgren
authors.forename: Richard
authors.initials: R
authors.lastname: Rosenquist
authors.forename: Birgitta
authors.initials: B
authors.lastname: Swolin
authors.forename: Bertil
authors.initials: B
authors.lastname: Johansson
mesh_terms: D002648:Child; D002675:Child, Preschool; D002869:Chromosome Aberrations; D002874:Chromosome Mapping; D050676:Core Binding Factor Alpha 2 Subunit / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D006801:Humans; D007055:Iceland; D007945:Leukemia, Lymphoid / Q000235:genetics*; D012537:Scandinavian and Nordic Countries; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins; C095239:ETV1 protein, human; C493728:RUNX1 protein, human; D014157:Transcription Factors