We performed
Waldenström macroglobulinemia (WM) is an uncommon B-cell lymphoproliferative disorder characterized by bone marrow lymphoplasmacytic infiltration and by the presence of a monoclonal IgM immunoglobulin in the serum [
Immunoglobulin heavy chain gene (
Recently, whole genome sequencing in WM patients revealed a highly recurrent somatic mutation (
In the present study we characterized
A cohort of 36 WM patients was studied retrospectively. Diagnostic workout included physical examination, hematological and laboratory parameters, chest radiographs, and computed tomography scans of the thorax, abdomen, and pelvis. Bone marrow smears and biopsy as well as immunophenotype were performed in all patients, and lymph node histology was additionally performed in the cases with lymphadenopathy. International diagnostic criteria were used for the diagnosis of WM. Patients’ characteristics are shown in Table
Clinical and laboratory findings for the study’s WM patients.
Mean value (median value) | Range | |
---|---|---|
Age (years) | 65,5 (64) | 42–84 |
Gender (male/female) | ||
IPSS stage | 19/17 | |
1 | 45% | |
2 | 39% | |
3 | 16% | |
Bone marrow involvement | 46,7% (40%) | 5–100% |
Lymphadenopathy | 21% | |
Splenomegaly | 19% | |
Hepatomegaly | 9% | |
Extranodal sites | 3% | |
IgM (mg/dL) | 2777,2 (2500) | 138–7870 |
Hb (g/dL) | 10,9 (11,1) | 6–14,3 |
Platelets (×109/L) | 233,2 (234) | 60–472 |
WBC (×109/L) | 7,1 (6,7) | 2,1–16,8 |
B2M (mg/dL) | 4,1 (3,4) | 1,9–10,4 |
Abnormal (high) LDH | 27% |
Forty-five percent, 39% and 16%, of patients were staged 1, 2, and 3, respectively, according to IPSS [
The study was approved by the local ethical committee.
We analyzed genomic DNA extracted from patients’ blood and/or bone marrow samples (bone marrow mononuclear cells, bone marrow smears, and bone marrow biopsies).
Genomic DNA was extracted by standard protocols using QIAmp DNA Mini kit (QIAGEN) according to the manufacturer’s recommendations.
Immunoglobulin heavy chain VDJ locus was amplified by PCR using the Biomed-2 strategy with FR1 primers as previously described [
In order to confirm monoclonality in the remaining 10/36 samples, cloning techniques were used as follows: (1) ligation of the PCR product to pCRII-TOPO vector (Invitrogen) using TOPO TA Cloning Kit (Invitrogen) according to manufacturer’s recommendations, (2) transformation of One Shot TOP10 Chemically Competent
Each clonal DNA
Samples from 31 patients were also investigated for detection of
The SPSS software v.15 was used. Correlations between molecular findings and clinical parameters were assessed by the Mann-Whitney or by the chi-square test. Pictorial representation of survival curves was done by the Kaplan-Mayer method and their comparison by the log-rank test.
Thirty-six WM patients were studied. Two out of the 36 patients were excluded from the analysis, as in these two patients genomic DNA was extracted from peripheral blood and not bone marrow. Although these two patients had not lymphoma cells in blood (by morphology or immunophenotype analysis), monoclonality of
Electropherogram—after capillary electrophoresis in Agilent 2100 Bioanalyzer using Agilent DNA 1000 kit (Agilent Technologies)—of
We observed an
Distinctive
Segment | Number of patients | % |
---|---|---|
|
1 | 2,86 |
|
1 | 2,86 |
|
1 | 2,86 |
|
3 | 8,57 |
|
9 | 25,71 |
|
3 | 8,57 |
|
2 | 5,71 |
|
1 | 2,86 |
|
1 | 2,86 |
|
1 | 2,86 |
|
6 | 17,14 |
|
3 | 8,57 |
|
2 | 5,71 |
|
1 | 2,86 |
SHM was seen in all but three cases (91,4%). Mean percentages of mutations in all cases,
Mean (median) of somatic mutations’ percentage in different groups.
Mean (median) somatic mutations’ percentage | Range (%) | |
---|---|---|
In all 35* cases | 7,5% (7,3%) | 0–16,1 |
In 32 cases with mutated genes (<98% homology) | 8,1% (7,6%) | 2,83–16,1 |
In |
8% (8,3%) | 0–14,46 |
In |
9,4% (9,7%) | 2,83–14,46 |
In |
7,5% (8,1%) | 4,02–9,65 |
*34 patients, 1 with two clones;
The above-mentioned findings were compared with patients’ physical and routine laboratory workup results and no correlations were found nor was it the case with time to treatment or survival. Although in CLL the
Since
The findings were also compared with patients’ physical and routine laboratory workup results and no correlations were found nor was it the case with time to treatment or survival, as also described by Jiménez et al. [
Finally it should be mentioned that the mean of SHM levels of
In addition, the landscape is still unclear in this field as
WM
In addition to the known hyperrepresentation of the
The authors declare no conflict of interests.
The authors thank D. Palaiologou, E. Staikou, and A. Stefanou for excellent technical assistance.