Cytogenetic 2; 18 and 18; 22 translocation in chronic lymphocytic leukemia with juxtaposition of bcl-2 and immunoglobulin light chain genes.
The majority of follicular lymphoma cells carry the typical chromosome translocation 14;18, which juxtaposes the bcl-2 gene to the immunoglobulin heavy-chain (IgH) gene. Variant translocations of the bcl-2 gene to the Ig lambda or Ig kappa gene have been found by molecular biological techniques in a significant fraction (approximately 10%) of chronic lymphocytic leukemia (CLL). However, there have been no reports describing the presence of cytogenetic 18;22 and 2;18 translocations in CLL, in spite of extensive karyotypic studies. We present here two cases of CLL, one with cytogenetically detected t(2;18)(p11;q21) and the other with the t(18;22)(q21;q11). The molecular analysis revealed that these translocations juxtaposed the bcl-2 and immunoglobulin light-chain (IgL) genes. The t(18;22) broke the 5' flanking region of the bcl-2 gene and juxtaposed to the immunoglobulin lambda light-chain (Ig lambda) gene in a head-to-head configuration, as in the cases previously described. In the case of the t(2;18), the bcl-2 gene and immunoglobulin kappa light-chain (Ig kappa) gene were juxtaposed in a head-to-tail configuration, which is opposite to that expected from the orientation of the genes on chromosomes. The breakpoint was located within the 5' untranslated region of the bcl-2 gene. The results presented here indicate that the bcl-2/immunoglobulin light-chain (IgL) gene juxtaposition seen in a fraction of CLL is the result of cytogenetically detectable reciprocal chromosome translocations 2;18 and 18;22.
Tashiro
S
S
Department of Hematology, School of Medicine, Hiroshima University, Japan.
Takechi
M
M
Asou
H
H
Takauchi
K
K
Kyo
T
T
Dohy
H
H
Kikuchi
M
M
Kamada
N
N
Tsujimoto
Y
Y
D001483:Base Sequence; D002869:Chromosome Aberrations / Q000235:genetics*; D025063:Chromosome Disorders; D002887:Chromosomes, Human, Pair 18; D002889:Chromosomes, Human, Pair 2; D002892:Chromosomes, Human, Pair 22; D003001:Cloning, Molecular; D005803:Genes, Immunoglobulin; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000235:genetics*; D007621:Karyotyping; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics*; D008969:Molecular Sequence Data; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000235:genetics*; D019253:Proto-Oncogene Proteins c-bcl-2; D014178:Translocation, Genetic
D007147:Immunoglobulin Light Chains; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2