Trisomy 12 is uncommon in typical chronic lymphocytic leukaemias

Abstract

The incidence of trisomy 12 was studied by conventional chromosome analysis in 111 patients referred as B-cell chronic lymphocytic leukaemia (B-CLL). Fluorescent in situ hybridization (FISH) was also applied in 34 of those patients with either a normal karyotype or no analysable mitoses. By karyotyping, trisomy 12 was present in 11.7% (13/111), whereas additional FISH increased the incidence to 14.4% (16/111). When subdividing our cases in either typical CLL (n = 90), fulfilling the FAB classification criteria, or atypical CLL (n = 21), with one or more variations from those criteria, the incidence of +12 by metaphase analysis was 3% and 48%, respectively. Additional FISH increased the incidence to 4% and 57%. The most common aberration in atypical CLL was FMC7 positivity (n = 11), followed by CD5 negativity (n = 8), strong surface immunoglobulin staining (n = 7) and atypical morphology (n = 6). Trisomy 12 could only be demonstrated in a small proportion of neoplastic cells in all positive cases. By FISH and/or karyotyping, all available samples at diagnosis of the disease were positive.

Chromosomal abnormalities detected by multicolor fluorescence in situ hybridization in fine-needle aspirates from patients with small lymphocytic lymphoma are useful for predicting survival

“…The atypical lymphocytes in SLL/CLL patients may also have immunophenotypic variations, such as lack of expression of CD5, strong immunoglobulin light chain staining, and FMC-7 reactivity. 24 In addition, trisomy 12 has been associated with high proliferation rates and poor prognosis 6 ; however, this was not a finding in the current study. When trisomy 12 is associated with complex karyotypes, there is an increased risk of transformation to Richter syndrome.…”

“…1 In SLL, the incidence of trisomy 12 ranges from 10% to 55% using FISH, 9 and its presence is associated with an atypical morphology. 6,24,25 In the current study. trisomy 12 was not observed more frequently in SLLacc, although this group is not analogous to atypical SLL.…”

Atypical lymphocyte morphology: an adverse prognostic factor for disease progression in stage A CLL independent of trisomy 12

“…In contrast, the survival of patients with deletions or translocations of chromosome 13q14, which is the other common cytogenetic abnormality in CLL, was no different from patients with a normal karyotype. More recently, we and others have drawn attention to the association between trisomy 12 and atypical lymphocyte morphology (Que et al, 1993;Criel et al, 1994Criel et al, , 1997Matutes et al, 1996).…”

“…Trisomy 12 has been reported to be common in both kinds of atypical CLL (Que et al, 1993;Criel et al, 1994Criel et al, , 1997Matutes et al, 1996), and both trisomy 12 and atypical morphology are more common in advanced stage.…”

B-cell chronic lymphocytic leukemia: Recent progress in biology, diagnosis, and therapy

“…Chromosomal abnormalities prevail in the advanced phases of the disease and in most instances are acquired events [14,19]. Trisomy 12 is associated with atypical morphology, advanced disease, and poor prognosis and is better detected by fluorescence in situ hybridization (FISH) [16,17]. In turn, del(6)(q21q23) has been associated with an increased proportion of prolymphocytes in peripheral blood [18].…”