University Clinic for Hematology, Macedonia
Title: Mutational Status of IGVH in correlation with Genetic Abnormalities of Patients with Chronic Lymphocytic Leukemia in Macedonia - Single Centre Experience
Sanja Trajkova is a specialist in Internal Medicine in the University Clinic for Hematology, Macedonia.
Background: B-cell chronic lymphocytic leukemia (CLL) is a clinically heterogeneous disease with many patients surviving for decades with watch and wait strategy or no treatment, whereas others have inferior survival despite therapy. In recent years, new molecular prognostic factors approached that have significantly improved the stratification of the CLL patients. One of the most important molecular predictors, the immunoglobulin VH gene mutational status, divides CLL into two prognostic groups, where unmutated U-CLL are associated with remarkably worse prognosis than mutated M-CLL. In many studies multiple recurring chromosomal aberrations appear to be effective prognostic markers in CLL. The most common abnormalities include 11q deletions, trisomy 12, 17p deletions and 13q deletions. The aim of the study was first time evaluation of rearrangement of IG genes and genetic abnormalities in Macedonian CLL patients. Methods: In this study, mutational status and configuration of IGHV-IGHD-IGHJ rearrangements in 70 treatment naïve CLL patients were analyzed using reverse transcriptase– polymerase chain reaction (RT-PCR) and sequencing methodology at the center for bimolecular pharmaceutical analyses, faculty of pharmacy, Skopje, Macedonia. We used multiplex ligation-dependent probe amplification (MLPA) for detection of most common genetic abnormalities. Results: Our evaluation have shown that 54.7% patients belonged to the U-CLL subset, whereas 45.3% belonged to the M-CLL subset. The most frequently expressed IGHV subgroup was IGHV3 (40%), followed by IGHV4 (29%), IGHV1(27%) and IGHV5 (3%). The most frequent subgroup with 8% were IGHV1-69*13 and IGHV4-34*0. In the IGHD and IGHJ sets most frequently expressed was IGHD3 (59.7%), IGHJ6 gene (53.1%) respectively. We found that 80% of IGHV1, 65.6% of IGHD3 and 83.3% of IGHJ6 gene were U-CLL (p=0.0005). Frequency of genetic aberrations by MLPA were 13q14 deletion (20%) follow by 11q deletion (14%) then trisomy 12 (13%)and 17p deletion (6.6%),multipal mutations(6.7%) and NOTCH mutation(5.3%). Conclusions: Our evaluation of mutational status on IGVH, IGDH, and IGJH gene in Macedonian CLL patients resulted with data which are consubstantial to those from Mediterranean area. Novel mutations discovered in this study must be validated through large cohort studies and may offer clues to the mechanisms underlying the difference in CLL survival. In the future, therapeutic strategies targeting these genes should be evaluated and considered. This is the first mutation analysis of CLL patients in Macedonia using next generation sequencing.