[Overrepresentation of specific gene segments of expressed immunoglobulin heavy chain variable region among unmutated and mutated patients with chronic lymphocytic leukemia]

Abstract

Objective: To investigate the overrepresentation of specific gene segments of immunoglobulin heavy chain variable region (IgVH) among unmutated and mutated chronic lymphocytic leukemia (CLL) patients and its prognostic implication.

Methods: Multiplex PCR was used to identify the expression of IgVH segment and its mutation status in CLL.

Results: Analyses were successfully performed in 80 of 85 samples. Marked skewed IgVH families were disclosed. The most commonly used VH was VH3 (40.0%), followed by VH4 (30.0%), VHI (13.8%), VH2 (10.0%) and VH5, VH7 (2.5%). Fifty-six patients (70.0%) had mutated VH, 24 (30.0%) unmutated VH. Nine cases (11.3%) were with 100% germline sequence. Fifteen cases (15/24, 62.5%) in VH4, 29 (29/32, 90.7%) in VH3, and 4 (4/11, 36.3%) in VH1 had mutated VH. The most frequently used IgVH gene was VH4-39 (13.8%), and VH4-34 (8.8%). J4 (36/66, 54.5%) and D3 (25/66, 37.8%) were the most frequently used in J and D genes. The progression-free survival (PFS) was 82 and 17 months (P = 0.000), and the overall survival (OS) was 90 and 41 months (P = 0.009), respectively, for mutated and unmutated cases. Recurrent CDR3 sequences were found in our patients and 2 patients with VH1-69 had CDR3 sequences highly similar to those reported in literature.

Conclusion: There is difference in IgVH gene segment usage and mutational status in different area CLL patients. Recurrent CDR3 sequences were found in specific IgVH gene segments, which highlights the importance of immunoglobulin mediated stimulation in the development of CLL.