Microsatellite instability analysis in typical and progressed mantle cell lymphoma and B-cell chronic lymphocytic leukemia.

BACKGROUND AND

OBJECTIVES

Microsatellite instability (MSI) is characterized by tumor-associated alterations in the germline size of microsatellite repeats caused by a reduced efficacy of the DNA mismatch repair machinery. The aim of this study was to investigate the presence of MSI in a number of cases of indolent and aggressive mantle cell lymphoma (MCL) and B-cell chronic lymphocytic leukemia (B-CLL) to determine its possible role in the initial development and progression of these disorders.

DESIGN AND

METHODS

We examined the presence of MSI in 28 B-CLL, 24 typical and 4 transformed B-CLL (Richter's syndrome) and 29 MCL, 19 typical and 10 blastoid variants by using a panel of 10 microsatellite markers and analyzed them using an AbiPrism 310 DNA sequencer. Fisher's exact test was used to compare categorical variables and Mann-Whitney's U-test for continuous variables.

RESULTS

MSI alterations were not observed in any case of MCL or Richter's syndrome and in only three (13%) patients with typical B-CLL. Two of these patients also had loss of heterozygosity in one of the 10 sites examined. These patients presented with a more advanced stage, diffuse bone marrow involvement, and poorer performance status than patients without these alterations.

INTERPRETATION AND

CONCLUSIONS

These findings indicate that MSI is not involved in the pathogenesis or progression of B-CLL and MCL but may appear in a small subset of patients with advanced B-CLL.