title: Conventional and molecular cytogenetic characterization of Burkitt lymphoma with bone marrow involvement in Brazilian children and adolescents.
abstract: BACKGROUND
  Burkitt lymphoma/leukemia (BL/L) is cytogenetically characterized by the t(8;14)(q24;q32) or its variants, t(2;8)(p11;q21), and t(8;22)(q24;q11.2), which juxtapose the MYC oncogene to one of the three immunoglobulin loci. The overall cure rate of BL/L in children is 70-90%, but patients diagnosed with advanced-stage disease have a less favorable prognosis. It is possible that secondary chromosomal abnormalities contribute to this unfavorable prognosis via chemotherapy resistance, but the results of genetic studies have been inconsistent. This study aimed to identify and characterize secondary chromosomal abnormalities associated with the t(8;14) and its variants in children with French-American-British-L3 leukemia or Burkitt lymphoma with bone marrow involvement at the time of diagnosis.
  
  
  METHODS
  Chromosome analysis was based on G-banding. Fluorescence in situ hybridization technique was applied using IGH/MYC/CEP8 dual-fusion and MYC break-apart probes. Multicolor chromosome banding was performed according to standard protocol.
  
  
  RESULTS
  We describe a group of BL/L with extreme adverse clinical outcome, in which secondary chromosomal abnormalities, particularly those involving the long arms of chromosomes 1 and 13, were found in 71% of cases. The IGH/MYC fusion showed molecular heterogeneity in 14% of cases and two cases exhibited three IGH/MYC fusion signals.
  
  
  CONCLUSIONS
  Secondary chromosomal abnormalities were found in a high proportion of patients. We observed an extent of IGH/MYC heterogeneity not previously reported in Burkitt lymphoma, including the novel finding of three fusion signals in two cases.
authors.affiliation: Post Graduation Program in Oncology, National Cancer Institute, Rio de Janeiro, RJ, Brazil; Cytogenetics Department, Bone Marrow Transplantation Unit, National Cancer Institute, Rio de Janeiro, RJ, Brazil; National Institute of Science and Technology for Cancer Control, Rio de Janeiro, Brazil.
authors.forename: Mariana T
authors.initials: MT
authors.lastname: De Souza
authors.forename: Rocio
authors.initials: R
authors.lastname: Hassan
authors.forename: Thomas
authors.initials: T
authors.lastname: Liehr
authors.forename: Terezinha J
authors.initials: TJ
authors.lastname: Marques-Salles
authors.forename: Alice M
authors.initials: AM
authors.lastname: Boulhosa
authors.forename: Eliana
authors.initials: E
authors.lastname: Abdelhay
authors.forename: Raul C
authors.initials: RC
authors.lastname: Ribeiro
authors.forename: Maria Luiza Macedo
authors.initials: ML
authors.lastname: Silva
mesh_terms: D000293:Adolescent; D001853:Bone Marrow / Q000473:pathology*; D001938:Brazil; D002051:Burkitt Lymphoma / Q000235:genetics / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D020223:Chromosome Painting; D002877:Chromosomes, Human / Q000235:genetics*; D003582:Cytogenetics; D005260:Female; D006801:Humans; D008297:Male; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D014178:Translocation, Genetic
chemical_list: D015514:Oncogene Proteins, Fusion
keywords: Burkitt lymphoma/leukemia; IGH/MYC gene fusion; pediatric; secondary chromosomal abnormalities; t(8 ;14)(q24 ;q32)