Abstract
BackgroundOur aim was to set the FISH combination of del(17p13), t(4;14), 1q21 gain and del(1p32), four adverse cytogenetic factors rarely evaluated together, and compare our technical thresholds with those defined in the literature.MethodsTwo hundred thirty-three patients with MM at diagnosis were studied using FISH to target 4 unfavorable cytogenetic abnormalities: 17p13 deletion, t(4;14) translocation, 1p32 deletion and 1q21 gain. Technical thresholds were determined for each probe using isolated CD138-expressing PC from patients without MM.ResultsThe FISH analysis identified abnormalities in 79.0% of patients. Del(17p13) was detected in 15.0% of cases, t(4;14) in 11.5%, 1q21 gain in 37.8% and del(1p32) in 8.7%. Adding 1p32/1q21 FISH probes has enabled us to identify adverse cytogenetic profiles in 39.0% of patients without del(17p13) or t(4;14). Clonal heterogeneity was observed in 51.1% of patients as well as an increase in the number of adverse abnormalities when related clones were greater than or equal to 2 (85.1% against 45.6%).ConclusionFISH allowed detecting accumulation of adverse abnormalities and clonal heterogeneity in MM with a combination of 4 probes. The impacts of these two parameters need to be evaluated, and could be included in future cytogenetic classifications.
Highlights
Our aim was to set the fluorescence in-situ hybridization (FISH) combination of del(17p13), t(4;14), 1q21 gain and del(1p32), four adverse cytogenetic factors rarely evaluated together, and compare our technical thresholds with those defined in the literature
Multiple Myeloma (MM) is a heterogeneous disease characterized by the clonal proliferation of abnormal plasma cells (PC), invading mainly the bone marrow (BM)
Plasma cell enrichment PC were enriched from BM mononuclear cells, using a magnetic cell-sorting CD138 MicroBeads kit (Miltenyi Biotec; BergischGlabach, Germany) according to the manufacturer’s protocol
Summary
Our aim was to set the FISH combination of del(17p13), t(4;14), 1q21 gain and del(1p32), four adverse cytogenetic factors rarely evaluated together, and compare our technical thresholds with those defined in the literature. Multiple Myeloma (MM) is a heterogeneous disease characterized by the clonal proliferation of abnormal plasma cells (PC), invading mainly the bone marrow (BM). MM accounts for approximately 1% of all cancers, and 10% of all hematopoietic neoplasms with a median age of 70 years at diagnosis [1]. The diagnosis of MM is Cytogenetic analysis plays a major role in the risk stratification of MM [2,3,4]. With a metaphase cytogenetic approach, only 35% of patients present abnormal karyotypes, often associated with an advanced stage of the disease [5]. Practice guidelines recommend interphase fluorescence in-situ hybridization (FISH) as the initial cytogenetic analysis for MM [6]. FISH is performed on isolated CD138-expressing plasma cells [7].
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