title: Clonal evolution as judged by immunoglobulin heavy chain gene rearrangements in relapsing precursor-B acute lymphoblastic leukemia.
abstract: Oligoclonality and ongoing clonal evolution are common features in patients with precursor-B (pre-B) acute lymphoblastic leukemia (ALL), as judged by immunoglobulin heavy chain (IgH) gene rearrangement analysis. These features are considered to be results of secondary rearrangements after malignant transformation or emergence of new tumor clones. In the present study we analyzed the IgH gene rearrangement status in 18 cases with relapsing pre-B ALL using variable heavy chain (V(H)) gene family specific polymerase chain reaction (PCR) amplification and single stranded conformation polymorphism (SSCP) analysis. Clonal IgH rearrangements were displayed in all leukemias but one, and altered rearrangement patterns occurred in five cases (29%), which were selected for detailed nucleotide sequence analysis. In one case, multiple subclones at diagnosis were suggested to be derived from a progenitor clone through joining of different V(H) germline gene segments to a pre-existing D-J(H) complex (V(H) to D-J(H) joining). Evidence for V(H) gene replacement with identical N-sequences at the V(H)-D junction and a common D-J(H) region was observed in one case. Diversification at the V(H)-D junction consisting of heterogeneous N-sequences were observed in one case. This molecular modification of the V(H)-D region could fit a hypothesized "open-and-shut" mechanism. Nevertheless, despite these ongoing events at least one IgH rearrangement remained unchanged throughout the disease in most patients, indicating that the immunoglobulin heavy chain locus can be a suitable marker for detection of minimal residual disease (MRD).
authors.affiliation: Department of Pathology, Umeå University, Sweden. richard.rosenquist@pathol.umu.se
authors.forename: R
authors.initials: R
authors.lastname: Rosenquist
authors.forename: U
authors.initials: U
authors.lastname: Thunberg
authors.forename: A H
authors.initials: AH
authors.lastname: Li
authors.forename: E
authors.initials: E
authors.lastname: Forestier
authors.forename: G
authors.initials: G
authors.lastname: Lönnerholm
authors.forename: J
authors.initials: J
authors.lastname: Lindh
authors.forename: C
authors.initials: C
authors.lastname: Sundström
authors.forename: J
authors.initials: J
authors.lastname: Sällström
authors.forename: D
authors.initials: D
authors.lastname: Holmberg
authors.forename: G
authors.initials: G
authors.lastname: Roos
mesh_terms: D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D002999:Clone Cells; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D005260:Female; D015321:Gene Rearrangement; D005803:Genes, Immunoglobulin / Q000235:genetics; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics; D007223:Infant; D008297:Male; D008969:Molecular Sequence Data; D009364:Neoplasm Recurrence, Local; D018807:Polymorphism, Single-Stranded Conformational; D015452:Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004273:DNA, Neoplasm; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region