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Japanese B cell chronic lymphocytic leukaemia: a cytogenetic and molecular biological study
Insights
Japanese B cell chronic lymphocytic leukemia (B-CLL) shares biological similarities with Western cases despite lower incidence. Genetic analyses reveal comparable gene rearrangements but a higher frequency of complex karyotypes in Japanese patients.
Area of Science:
- Hematology
- Oncology
- Genetics
Background:
- Japanese B cell chronic lymphocytic leukemia (B-CLL) has a lower incidence compared to Western countries.
- Understanding the pathophysiology of B-CLL in Japan is crucial due to this epidemiological difference.
Purpose of the Study:
- To clarify the pathophysiology of Japanese B-CLL.
- To compare the clinical, cytogenetic, and molecular genetic features of Japanese B-CLL with those in Western populations.
Main Methods:
- Clinical and laboratory features were assessed in 55 Japanese B-CLL patients.
- Cytogenetic analysis (chromosome studies) was performed on 48 patients.
- Molecular genetic studies (Southern blot analysis) investigated bcl-1, bcl-2, and bcl-3 gene rearrangements.
Main Results:
- Clinical and laboratory features of Japanese B-CLL were similar to Western patients.
- Clonal chromosome aberrations were found in 45.8% of patients; non-clonal in 29.2%.
- Common aberrations included trisomy 12 and 14q/13q abnormalities. Complex karyotypes were more frequent than in Western countries. Gene rearrangements (bcl-1, bcl-2, bcl-3) were similar to Western B-CLL.
Conclusions:
- The biological characteristics of Japanese B-CLL are largely similar to those in Western countries.
- The lower incidence in Japan may be linked to racial differences.
- Further research into genetic factors is warranted to explain incidence disparities.
Abstract:
Clinical, cytogenetic, and molecular genetic studies were performed to clarify the pathophysiology of Japanese B cell chronic lymphocytic leukaemia (B-CLL), since the incidence of B-CLL in Japan is significantly lower than in western countries. The clinical and laboratory features of 55 Japanese patients with B-CLL in this study did not differ from those of Americans or Europeans with B-CLL. In the chromosome analyses, suitable metaphases with good band quality were obtained from 48 patients (87.2%), of whom 22 patients (45.8%) showed clonal chromosome aberrations and 14 (29.2%) had non-clonal aberrations. Trisomy 12 and abnormalities of 14q and 13q were found in four (18.2%), two (9.1%) and six patients (27.2%), respectively. There were no particular chromosome abnormalities or specific breakpoints in Japanese B-CLL. However, complex karyotype was found in higher incidence than in western countries. In the Southern blot analyses, rearranged band patterns were observed in the major breakpoint region (mbr) of the bcl-2 gene in one case, in the 5'-breakpoint region (5'-bcl-2) in two, and bcl-3 in one. Of the two patients with 5'-bcl-2 rearrangements, one had a normal karyotype and the other had t(2;18)(p12;q21). The incidence of rearrangements of the bcl-1, bcl-2 and bcl-3 genes in Japanese B-CLL was similar to that in western countries. These findings suggest that the biological characteristics of B-CLL in Japan are almost the same as those in western countries, although the incidence of B-CLL in Japan is quite different; this may be related to racial differences, which seem to be an important factor in the development of B-CLL.