title: ETV6-AML1 translocation breakpoints cluster near a purine/pyrimidine repeat region in the ETV6 gene.
abstract: The t(12;21)(p13;q22) translocation, fusing the ETV6 and AML1 genes, is the most frequent chromosomal translocation associated with pediatric B-cell precursor acute lymphoblastic leukemia. Although the genomic organization of the ETV6 gene and a breakpoint cluster region (bcr) in ETV6 intron 5 has been described, mapping of AML1 breakpoints has been hampered because of the large, hitherto unknown size of AML1 intron 1. Here, we report the mapping of the AML1 gene between exons 1 and 3, cloning of ETV6-AML1 breakpoints from different patients, and localization of the AML1 breakpoints within AML1 intron 1. In contrast to the tightly clustered ETV6 breakpoints, the AML1 breakpoints were found to be dispersed throughout AML1 intron 1. Although nucleotide sequence analysis of the breakpoint junctions showed several 5/7 matches for the V(D)J consensus heptamer recognition sequence, these matches were present only on the ETV6 alleles and not on the AML1 alleles, making it unlikely that the translocations were mediated by a simple V(D)J recombination mistake. Interestingly, several breakpoints as well as a stable insertion polymorphism mapped close to a polymorphic, alternating purine-pyrimidine tract in the ETV6 gene, suggesting that this region may be prone to DNA recombination events such as insertions or translocations. Finally, the presence of an insertional polymorphism within the ETV6 bcr must be recognized to avoid incorrect genotype designation based on Southern blot analysis.
authors.affiliation: Departments of Cancer Genetics, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
authors.forename: S P
authors.initials: SP
authors.lastname: Thandla
authors.forename: J E
authors.initials: JE
authors.lastname: Ploski
authors.forename: S Z
authors.initials: SZ
authors.lastname: Raza-Egilmez
authors.forename: P P
authors.initials: PP
authors.lastname: Chhalliyil
authors.forename: A W
authors.initials: AW
authors.lastname: Block
authors.forename: P J
authors.initials: PJ
authors.lastname: de Jong
authors.forename: P D
authors.initials: PD
authors.lastname: Aplan
mesh_terms: D001483:Base Sequence; D002051:Burkitt Lymphoma / Q000235:genetics / Q000473:pathology; D019457:Chromosome Breakage / Q000235:genetics*; D003001:Cloning, Molecular; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins / Q000235:genetics*; D005091:Exons; D052138:Genes, Neoplasm; D005820:Genetic Testing; D006801:Humans; D008969:Molecular Sequence Data; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D011687:Purines / Q000378:metabolism; D011743:Pyrimidines / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D012097:Repressor Proteins; D014157:Transcription Factors / Q000235:genetics*; D014178:Translocation, Genetic / Q000235:genetics*; D000097764:ETS Translocation Variant 6 Protein
chemical_list: D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins; D015514:Oncogene Proteins, Fusion; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D011687:Purines; D011743:Pyrimidines; D012097:Repressor Proteins; D014157:Transcription Factors; D000097764:ETS Translocation Variant 6 Protein; C493728:RUNX1 protein, human