title: Sequential and hierarchical chromosomal changes and chromosome instability are distinct features of high hyperdiploid pediatric acute lymphoblastic leukemia.
abstract: BACKGROUND
  Pathogenesis of the non-random accumulation of extra chromosomes in the low and high hyperdiploid (HeL, HeH) pre-B pediatric acute lymphoblastic leukemia (B-pALL) is largely unknown, and has been clarified with respect only to tetrasomic chromosomes. We analyzed the hierarchy of changes in chromosome number and chromosomal instability, as well as clonal heterogeneity and evolution, in the untreated bone marrow cell samples from 214 B-pALL patients.
  
  
  METHODS
  Applying relocation, 2 × 4 color interphase fluorescence in situ hybridization was used to detect copy number alterations (CNAs) of the most commonly involved chromosomes, 4, 6, 10, 14, 17, 18, 21, and X. This approach allowed us to acquire a dataset correlated for all eight parameters.
  
  
  RESULTS
  Based on chromosome number, an average of 6.9 and 10.2, whereas according to unique constellation 15.3 and 26.7 subclones could be identified in the HeL and HeH subgroups, respectively. Cluster analysis revealed the order of CNAs to chromosomes was highly conserved, and network analysis indicated changes in chromosome number were sequential for 80-90% of all numerical aberrations. Significant chromosome instability was revealed in both subgroups of leukemia.
  
  
  CONCLUSIONS
  Data generated using this new approach indicate that chromosomal instability, which causes heterogeneity in the subclonal landscape, and the sequential changes to chromosome numbers, are both determining factors in the pathomechanism of the hyperdiploid B-pALL. These new observations could prompt research into the mitotic machinery of leukemic cells to identify new therapeutic targets for treating this disease.
authors.affiliation: Department of Pathology, University of Pécs Medical Center, Pécs, Hungary.
authors.forename: Donát
authors.initials: D
authors.lastname: Alpár
authors.forename: Gábor
authors.initials: G
authors.lastname: Pajor
authors.forename: Péter
authors.initials: P
authors.lastname: Varga
authors.forename: Béla
authors.initials: B
authors.lastname: Kajtár
authors.forename: László
authors.initials: L
authors.lastname: Pótó
authors.forename: Róbert
authors.initials: R
authors.lastname: Mátics
authors.forename: Agnes
authors.initials: A
authors.lastname: Vojcek
authors.forename: Gábor
authors.initials: G
authors.lastname: Ottoffy
authors.forename: Károly
authors.initials: K
authors.lastname: Szuhai
authors.forename: László
authors.initials: L
authors.lastname: Pajor
mesh_terms: D002648:Child; D043171:Chromosomal Instability / Q000235:genetics*; D002869:Chromosome Aberrations; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000235:genetics*; D011003:Ploidies; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics*; D011379:Prognosis
keywords: clonal architecture; hyperdiploidy; iFISH; lymphoblastic leukemia