title: IgV gene intraclonal diversification and clonal evolution in B-cell chronic lymphocytic leukaemia.
abstract: Intraclonal diversification of immunoglobulin (Ig) variable (V) genes was evaluated in leukaemic cells from a B-cell chronic lymphocytic leukaemia (B-CLL) case over a 2-year period at four time points. Intraclonal heterogeneity was analysed by sequencing 305 molecular clones derived from polymerase chain reaction amplification of B-CLL cell IgV heavy (H) and light (C) chain gene rearrangements. Sequences were compared with evaluating intraclonal variation and the nature of somatic mutations. Although IgV intraclonal variation was detected at all time points, its level decreased with time and a parallel emergence of two more represented V(H)DJ(H) clones was observed. They differed by nine nucleotide substitutions one of which only caused a conservative replacement aminoacid change. In addition, one V(L)J(L) rearrangement became more represented over time. Analyses of somatic mutations suggest antigen selection and impairment of negative selection of neoplastic cells. In addition, a genealogical tree representing a model of clonal evolution of the neoplastic cells was created. It is of note that, during the period of study, the patient showed clinical progression of disease. We conclude that antigen stimulation and somatic hypermutation may participate in disease progression through the selection and expansion of neoplastic subclone(s).
authors.affiliation: Department of Experimental Medicine, Human Anatomy Section, University of Genoa, Genoa, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Bagnara
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Callea
authors.forename: Caterina
authors.initials: C
authors.lastname: Stelitano
authors.forename: Fortunato
authors.initials: F
authors.lastname: Morabito
authors.forename: Sonia
authors.initials: S
authors.lastname: Fabris
authors.forename: Antonino
authors.initials: A
authors.lastname: Neri
authors.forename: Sabrina
authors.initials: S
authors.lastname: Zanardi
authors.forename: Fabio
authors.initials: F
authors.lastname: Ghiotto
authors.forename: Ermanno
authors.initials: E
authors.lastname: Ciccone
authors.forename: Carlo Enrico
authors.initials: CE
authors.lastname: Grossi
authors.forename: Franco
authors.initials: F
authors.lastname: Fais
mesh_terms: D000368:Aged; D002999:Clone Cells; D004252:DNA Mutational Analysis; D018450:Disease Progression; D019143:Evolution, Molecular; D015321:Gene Rearrangement; D005803:Genes, Immunoglobulin; D014644:Genetic Variation; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics*; D008213:Lymphocyte Activation; D008297:Male; D011947:Receptors, Antigen, B-Cell / Q000276:immunology; D016415:Sequence Alignment; D027041:Somatic Hypermutation, Immunoglobulin
chemical_list: D007135:Immunoglobulin Variable Region; D011947:Receptors, Antigen, B-Cell