Contributions
Abstract: EP763
Type: E-Poster Presentation
Session title: Hematopoiesis, stem cells and microenvironment
Background
Ring chromosomes are uncommon and poorly investigated cytogenetic abnormalities in hematological malignancies.
Aims
The aim of the study was to shed light to the nature of ring chromosomes in bone marrow samples from patients with hematological malignancies and to identify the spectrum of chromosomal abnormalities in addition to ring chromosomes, by conventional and molecular cytogenetic analysis.
Methods
This study includes 40 patients with ring chromosomes identified among 28.821 patients with hematological malignancies from 1998 until 2019. The cytogenetic analysis was performed on 24h and 48h unstimulated bone marrow cultures using GTG-banding. Karyotypes were described according to the international system for human cytogenomic nomenclature (ISCN) 2016. Molecular cytogenetic analysis was performed by fluorescence in situ hybridization (FISH) using probes for the centromere of chromosomes (CEP) 1, 3, 7, 8, 9, 11 and for chromosomal regions 8q24.21 (MYC gene), 11q23 (MLL gene) and 17p13 (p53 gene) chosen each time according to karyotype and diagnosis. For each sample, 10 metaphases (mFISH) at least were analyzed.
Results
The frequency of ring chromosomes in hematological malignancies was ~ 0,14%. Among our patients with ring chromosomes, 48,5% had AML, 33,5% MDS, 6% MPD, 9% LPD and 3% ALL. The sex ratio was 1.1 (21 males/19 females) and the mean age was 67.6 years (range 12-91). Ring chromosomes were found as a sole abnormality in 2 patients (5%), with one more abnormality in 4 (10%) and in complex karyotypes in 34 patients (85%). The most frequent additional abnormality was marker chromosomes (51.2%), followed by -5/del(5q) (43,8%), -7/del(7q) (34,1%), -11 (26.8%), +8 (24.3%), -21 (19.5%), -17 (17.1%), -18 (14.6%). The nature of ring chromosomes was identified in 16 cases by mFISH and revealed: a) CEP 11 accompanied by MLL amplification in 9/16 (56.3%) all in complex karyotypes in AML or MDS cases. b) MYC amplification without CEP 8 in 2/16 (12.5%) as a sole abnormality. c) CEP 7 in 2/16 (12.5%) cases without additional abnormality in the karyotype except -7. d) CEP 1, 3 and 9 and TP53 gene in 1/16 (6.3%) each.
Conclusion
Ring chromosomes are very rare aberrations in hematological malignancies. They are observed mainly in AML and MDS, in elderly patients and in complex karyotypes. The most frequent additional abnormalities are marker chromosomes, -5/del(5q) and -7/del(7q). The most common origin of ring chromosome was that of chromosome 11, accompanied simultaneously by MLL amplification.
Keyword(s): AML, Chromosomal abnormality, Complex aberrant karyotype, Fluorescence in situ hybridization
Abstract: EP763
Type: E-Poster Presentation
Session title: Hematopoiesis, stem cells and microenvironment
Background
Ring chromosomes are uncommon and poorly investigated cytogenetic abnormalities in hematological malignancies.
Aims
The aim of the study was to shed light to the nature of ring chromosomes in bone marrow samples from patients with hematological malignancies and to identify the spectrum of chromosomal abnormalities in addition to ring chromosomes, by conventional and molecular cytogenetic analysis.
Methods
This study includes 40 patients with ring chromosomes identified among 28.821 patients with hematological malignancies from 1998 until 2019. The cytogenetic analysis was performed on 24h and 48h unstimulated bone marrow cultures using GTG-banding. Karyotypes were described according to the international system for human cytogenomic nomenclature (ISCN) 2016. Molecular cytogenetic analysis was performed by fluorescence in situ hybridization (FISH) using probes for the centromere of chromosomes (CEP) 1, 3, 7, 8, 9, 11 and for chromosomal regions 8q24.21 (MYC gene), 11q23 (MLL gene) and 17p13 (p53 gene) chosen each time according to karyotype and diagnosis. For each sample, 10 metaphases (mFISH) at least were analyzed.
Results
The frequency of ring chromosomes in hematological malignancies was ~ 0,14%. Among our patients with ring chromosomes, 48,5% had AML, 33,5% MDS, 6% MPD, 9% LPD and 3% ALL. The sex ratio was 1.1 (21 males/19 females) and the mean age was 67.6 years (range 12-91). Ring chromosomes were found as a sole abnormality in 2 patients (5%), with one more abnormality in 4 (10%) and in complex karyotypes in 34 patients (85%). The most frequent additional abnormality was marker chromosomes (51.2%), followed by -5/del(5q) (43,8%), -7/del(7q) (34,1%), -11 (26.8%), +8 (24.3%), -21 (19.5%), -17 (17.1%), -18 (14.6%). The nature of ring chromosomes was identified in 16 cases by mFISH and revealed: a) CEP 11 accompanied by MLL amplification in 9/16 (56.3%) all in complex karyotypes in AML or MDS cases. b) MYC amplification without CEP 8 in 2/16 (12.5%) as a sole abnormality. c) CEP 7 in 2/16 (12.5%) cases without additional abnormality in the karyotype except -7. d) CEP 1, 3 and 9 and TP53 gene in 1/16 (6.3%) each.
Conclusion
Ring chromosomes are very rare aberrations in hematological malignancies. They are observed mainly in AML and MDS, in elderly patients and in complex karyotypes. The most frequent additional abnormalities are marker chromosomes, -5/del(5q) and -7/del(7q). The most common origin of ring chromosome was that of chromosome 11, accompanied simultaneously by MLL amplification.
Keyword(s): AML, Chromosomal abnormality, Complex aberrant karyotype, Fluorescence in situ hybridization