THE ASXL1 GENE ALTERATIONS IN BONE MARROW CELLS OF PATIENTS WITH DELETION 20Q AND MYELOID DISORDERS
(Abstract release date: 05/19/16)
EHA Library. Brezinova J. 06/09/16; 134804; PB1904
Dr. Jana Brezinova
Contributions
Contributions
Abstract
Abstract: PB1904
Type: Publication Only
Background
In recent years, identification of gene mutations together with chromosomal aberrations allows the better characterization and treatment stratification of patients with myeloid disorders. Deletion of 20q - del(20q) - is a recurrent abnormality observed in myelodysplastic syndromes (MDSs), myeloproliferative neoplasms (MPNs), or acute myeloid leukemia (AML). As a sole aberration this finding gives a good prognosis. In our previous study we proved a fusion of the ASXL1 and TSHZ2 genes resulting in an isodicentric chromosome of a deleted 20q in a patient with MDS. The ASXL1 gene maps to chromosome region 20q11.21 and in contrast with del(20q) recurrent mutations in this gene are generally associated with poor prognosis.
Aims
The aim of this study was to determine the frequency of ASXL1 gene alterations in bone marrow cells of patients with del(20q) and/or with ider(20q) as a sole aberration and to characterize the breakpoints with molecular cytogenetic techniques.
Methods
Fluorescence in situ hybridizations (FISH) with locus specific probes for 20q11 and 20q12 regions (Abbott, Kreatech) confirmed the cytogenetically observed deletions of 20q in a cohort of 21 patients (15 male, 6 female, median age 69 years) with myeloid disorders (MDS 14x, MPN 3x, myelofibrosis 2x, thrombocytopenia 2x). In nineteen patients deletion of 20q was a sole aberration, in two patients an isodicentric chromosome of deleted 20q was detected by FISH with a subtelomeric probe 20p/20q (Abbott). Metaphase FISH mapping with a set of four bacterial artificial chromosome (BAC) probes (BlueGnome) localized in 20q11.21 and 20q13.2 was used to determine the breakpoints. Array comparative genomic hybridization (aCGH, CytoChip Cancer 4x180K v2.0, BlueGnome/Illumina) was performed on DNA samples of bone marrow cells of 11 patients with suspected ASXL1 gene deletion to find out the gene copy number variation.
Results
A weak signal of RP11-358N2 BAC probe (30.93-31.12 Mb from telomere on the short arm, 20q11.21) was observed in six patients (29%), suggesting the proximal breakpoint of the deletion in the ASXL1 gene (30.95-31.03 Mb, 20q11.21). However, the distal breakpoint in the TSHZ2 gene (51.80-52.11 Mb; 20q13.2) was found in one patient only. In seven patients (33%) the signal of RP11-358N2 BAC probe was not present on the derivative chromosome confirming the ASXL1 gene deletion. In the remaining eight patients the proximal breakpoint of the deletion was determined distally to the ASXL1 gene. In the group of six patients with proximal breakpoint in ASXL1 gene aCGH determined the breakpoint: in one patient in exon 1, in one patient in exon 4, in three patients behind the exon 4, in one patient in exon 5-8 and in one patient in exon 12. Five patients died in a group of thirteen patients with ASXL1 gene alteration.
Conclusion
Deletion 20q is assumed to play a key role in pathogenesis of myeloid malignancies. FISH with BAC probes used is a reliable fast technique that can point out patients with ASXL1 alterations and therefore potentially worse prognosis than expected. In our cohort, the ASXL1 gene was altered in thirteen out of twenty-one patients (62%). We suppose that the determination of the ASXL1 gene alterations in del(20q) cases may have the prognostic impact, but the relations with clinical data should be studied in a larger cohort of patients.Supported by MHCR project for conceptual development of research organization 00023736, RVO-VFN64165 and GACR P302/12/G157.
Session topic: E-poster
Keyword(s): FISH, Myelodysplasia
Type: Publication Only
Background
In recent years, identification of gene mutations together with chromosomal aberrations allows the better characterization and treatment stratification of patients with myeloid disorders. Deletion of 20q - del(20q) - is a recurrent abnormality observed in myelodysplastic syndromes (MDSs), myeloproliferative neoplasms (MPNs), or acute myeloid leukemia (AML). As a sole aberration this finding gives a good prognosis. In our previous study we proved a fusion of the ASXL1 and TSHZ2 genes resulting in an isodicentric chromosome of a deleted 20q in a patient with MDS. The ASXL1 gene maps to chromosome region 20q11.21 and in contrast with del(20q) recurrent mutations in this gene are generally associated with poor prognosis.
Aims
The aim of this study was to determine the frequency of ASXL1 gene alterations in bone marrow cells of patients with del(20q) and/or with ider(20q) as a sole aberration and to characterize the breakpoints with molecular cytogenetic techniques.
Methods
Fluorescence in situ hybridizations (FISH) with locus specific probes for 20q11 and 20q12 regions (Abbott, Kreatech) confirmed the cytogenetically observed deletions of 20q in a cohort of 21 patients (15 male, 6 female, median age 69 years) with myeloid disorders (MDS 14x, MPN 3x, myelofibrosis 2x, thrombocytopenia 2x). In nineteen patients deletion of 20q was a sole aberration, in two patients an isodicentric chromosome of deleted 20q was detected by FISH with a subtelomeric probe 20p/20q (Abbott). Metaphase FISH mapping with a set of four bacterial artificial chromosome (BAC) probes (BlueGnome) localized in 20q11.21 and 20q13.2 was used to determine the breakpoints. Array comparative genomic hybridization (aCGH, CytoChip Cancer 4x180K v2.0, BlueGnome/Illumina) was performed on DNA samples of bone marrow cells of 11 patients with suspected ASXL1 gene deletion to find out the gene copy number variation.
Results
A weak signal of RP11-358N2 BAC probe (30.93-31.12 Mb from telomere on the short arm, 20q11.21) was observed in six patients (29%), suggesting the proximal breakpoint of the deletion in the ASXL1 gene (30.95-31.03 Mb, 20q11.21). However, the distal breakpoint in the TSHZ2 gene (51.80-52.11 Mb; 20q13.2) was found in one patient only. In seven patients (33%) the signal of RP11-358N2 BAC probe was not present on the derivative chromosome confirming the ASXL1 gene deletion. In the remaining eight patients the proximal breakpoint of the deletion was determined distally to the ASXL1 gene. In the group of six patients with proximal breakpoint in ASXL1 gene aCGH determined the breakpoint: in one patient in exon 1, in one patient in exon 4, in three patients behind the exon 4, in one patient in exon 5-8 and in one patient in exon 12. Five patients died in a group of thirteen patients with ASXL1 gene alteration.
Conclusion
Deletion 20q is assumed to play a key role in pathogenesis of myeloid malignancies. FISH with BAC probes used is a reliable fast technique that can point out patients with ASXL1 alterations and therefore potentially worse prognosis than expected. In our cohort, the ASXL1 gene was altered in thirteen out of twenty-one patients (62%). We suppose that the determination of the ASXL1 gene alterations in del(20q) cases may have the prognostic impact, but the relations with clinical data should be studied in a larger cohort of patients.Supported by MHCR project for conceptual development of research organization 00023736, RVO-VFN64165 and GACR P302/12/G157.
Session topic: E-poster
Keyword(s): FISH, Myelodysplasia
Abstract: PB1904
Type: Publication Only
Background
In recent years, identification of gene mutations together with chromosomal aberrations allows the better characterization and treatment stratification of patients with myeloid disorders. Deletion of 20q - del(20q) - is a recurrent abnormality observed in myelodysplastic syndromes (MDSs), myeloproliferative neoplasms (MPNs), or acute myeloid leukemia (AML). As a sole aberration this finding gives a good prognosis. In our previous study we proved a fusion of the ASXL1 and TSHZ2 genes resulting in an isodicentric chromosome of a deleted 20q in a patient with MDS. The ASXL1 gene maps to chromosome region 20q11.21 and in contrast with del(20q) recurrent mutations in this gene are generally associated with poor prognosis.
Aims
The aim of this study was to determine the frequency of ASXL1 gene alterations in bone marrow cells of patients with del(20q) and/or with ider(20q) as a sole aberration and to characterize the breakpoints with molecular cytogenetic techniques.
Methods
Fluorescence in situ hybridizations (FISH) with locus specific probes for 20q11 and 20q12 regions (Abbott, Kreatech) confirmed the cytogenetically observed deletions of 20q in a cohort of 21 patients (15 male, 6 female, median age 69 years) with myeloid disorders (MDS 14x, MPN 3x, myelofibrosis 2x, thrombocytopenia 2x). In nineteen patients deletion of 20q was a sole aberration, in two patients an isodicentric chromosome of deleted 20q was detected by FISH with a subtelomeric probe 20p/20q (Abbott). Metaphase FISH mapping with a set of four bacterial artificial chromosome (BAC) probes (BlueGnome) localized in 20q11.21 and 20q13.2 was used to determine the breakpoints. Array comparative genomic hybridization (aCGH, CytoChip Cancer 4x180K v2.0, BlueGnome/Illumina) was performed on DNA samples of bone marrow cells of 11 patients with suspected ASXL1 gene deletion to find out the gene copy number variation.
Results
A weak signal of RP11-358N2 BAC probe (30.93-31.12 Mb from telomere on the short arm, 20q11.21) was observed in six patients (29%), suggesting the proximal breakpoint of the deletion in the ASXL1 gene (30.95-31.03 Mb, 20q11.21). However, the distal breakpoint in the TSHZ2 gene (51.80-52.11 Mb; 20q13.2) was found in one patient only. In seven patients (33%) the signal of RP11-358N2 BAC probe was not present on the derivative chromosome confirming the ASXL1 gene deletion. In the remaining eight patients the proximal breakpoint of the deletion was determined distally to the ASXL1 gene. In the group of six patients with proximal breakpoint in ASXL1 gene aCGH determined the breakpoint: in one patient in exon 1, in one patient in exon 4, in three patients behind the exon 4, in one patient in exon 5-8 and in one patient in exon 12. Five patients died in a group of thirteen patients with ASXL1 gene alteration.
Conclusion
Deletion 20q is assumed to play a key role in pathogenesis of myeloid malignancies. FISH with BAC probes used is a reliable fast technique that can point out patients with ASXL1 alterations and therefore potentially worse prognosis than expected. In our cohort, the ASXL1 gene was altered in thirteen out of twenty-one patients (62%). We suppose that the determination of the ASXL1 gene alterations in del(20q) cases may have the prognostic impact, but the relations with clinical data should be studied in a larger cohort of patients.Supported by MHCR project for conceptual development of research organization 00023736, RVO-VFN64165 and GACR P302/12/G157.
Session topic: E-poster
Keyword(s): FISH, Myelodysplasia
Type: Publication Only
Background
In recent years, identification of gene mutations together with chromosomal aberrations allows the better characterization and treatment stratification of patients with myeloid disorders. Deletion of 20q - del(20q) - is a recurrent abnormality observed in myelodysplastic syndromes (MDSs), myeloproliferative neoplasms (MPNs), or acute myeloid leukemia (AML). As a sole aberration this finding gives a good prognosis. In our previous study we proved a fusion of the ASXL1 and TSHZ2 genes resulting in an isodicentric chromosome of a deleted 20q in a patient with MDS. The ASXL1 gene maps to chromosome region 20q11.21 and in contrast with del(20q) recurrent mutations in this gene are generally associated with poor prognosis.
Aims
The aim of this study was to determine the frequency of ASXL1 gene alterations in bone marrow cells of patients with del(20q) and/or with ider(20q) as a sole aberration and to characterize the breakpoints with molecular cytogenetic techniques.
Methods
Fluorescence in situ hybridizations (FISH) with locus specific probes for 20q11 and 20q12 regions (Abbott, Kreatech) confirmed the cytogenetically observed deletions of 20q in a cohort of 21 patients (15 male, 6 female, median age 69 years) with myeloid disorders (MDS 14x, MPN 3x, myelofibrosis 2x, thrombocytopenia 2x). In nineteen patients deletion of 20q was a sole aberration, in two patients an isodicentric chromosome of deleted 20q was detected by FISH with a subtelomeric probe 20p/20q (Abbott). Metaphase FISH mapping with a set of four bacterial artificial chromosome (BAC) probes (BlueGnome) localized in 20q11.21 and 20q13.2 was used to determine the breakpoints. Array comparative genomic hybridization (aCGH, CytoChip Cancer 4x180K v2.0, BlueGnome/Illumina) was performed on DNA samples of bone marrow cells of 11 patients with suspected ASXL1 gene deletion to find out the gene copy number variation.
Results
A weak signal of RP11-358N2 BAC probe (30.93-31.12 Mb from telomere on the short arm, 20q11.21) was observed in six patients (29%), suggesting the proximal breakpoint of the deletion in the ASXL1 gene (30.95-31.03 Mb, 20q11.21). However, the distal breakpoint in the TSHZ2 gene (51.80-52.11 Mb; 20q13.2) was found in one patient only. In seven patients (33%) the signal of RP11-358N2 BAC probe was not present on the derivative chromosome confirming the ASXL1 gene deletion. In the remaining eight patients the proximal breakpoint of the deletion was determined distally to the ASXL1 gene. In the group of six patients with proximal breakpoint in ASXL1 gene aCGH determined the breakpoint: in one patient in exon 1, in one patient in exon 4, in three patients behind the exon 4, in one patient in exon 5-8 and in one patient in exon 12. Five patients died in a group of thirteen patients with ASXL1 gene alteration.
Conclusion
Deletion 20q is assumed to play a key role in pathogenesis of myeloid malignancies. FISH with BAC probes used is a reliable fast technique that can point out patients with ASXL1 alterations and therefore potentially worse prognosis than expected. In our cohort, the ASXL1 gene was altered in thirteen out of twenty-one patients (62%). We suppose that the determination of the ASXL1 gene alterations in del(20q) cases may have the prognostic impact, but the relations with clinical data should be studied in a larger cohort of patients.Supported by MHCR project for conceptual development of research organization 00023736, RVO-VFN64165 and GACR P302/12/G157.
Session topic: E-poster
Keyword(s): FISH, Myelodysplasia
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