Contributions
Abstract: PB2263
Type: Publication Only
Background
Myeloproliferative neoplasms (MPNs) are a group of clonal hematopoietic stem cell disorders, which are exceedingly rare and poorly understood in children. The reported frequency of JAK2 (V617F), MPL, CALR mutations is much lower in pediatric patients than in adults and the underlying genetics remain largely unknown.
Aims
The aim of our study was to characterize mutational profile of pediatric MPNs using next-generation sequencing (NGS).
Methods
The study included 19 patients diagnosed as Ph-negative MPN (11 boys and 8 girls). Essential thrombocythemia (ET) was diagnosed in 12 patients, polycythemia vera (PV) in 7 patients. The median manifestation age was 7.5 years (ranged from 3 months to 21 years).
Next-generation sequencing (NGS) was performed using MiSeq (Illumina, USA). Amplicon library was prepared using Human Myeloid Neoplasms Panel, № DHS-003Z (Qiagen, Germany), which included 141 genes. Fragment analysis of CALR gene exon 9 was performed for the detection of indels using ABI PRISM 3500 (Applied Biosystems).
Results
Classical JAK2(V617F) mutation was found in 9 patients: six patients with PV (86%) and two with ET (17%). Also JAK2 c.1613_1616delACAAinsT in exon 12 was found in one case with PV.
Mutations in CALR gene exon 9 were identified in four patients with ET (33%). Type 1 CALR frameshift mutation, a 52-bp del (p.L367fs*46) was found in two cases and one patient carried type 2 mutation, a 5-bp TTGTC insertion (p.K385fs*47), one patient harbored complex mutation c.1149-1154_delGGACAAinsTCCTTGTC(p.E383fs*48).
No additional somatic mutation in epigenetic regulators (ASXL1, IDH1/2, DMT3A) specific for adult MPN were observed in our group.
Investigation of 22 matched germline and somatic samples in 11 cases revealed the germline nature of the majority of additional mutation in epigenetic regulators (IDH2, TET2, EZH2, EP300, BCOR, CREBBP), in JAK-STAT negative regulators (SH2B3) and recurrent mismatch repair gene (MSH6), annotated as “possibly pathogenic” by predictive software.
One JAK2(V617F) positive PV patient carried germline mutation BLM c.1642C>T, which was described as the breast and prostate cancer predisposal mutation. This patient also had somatic mutation in BCOR c.4934C>G and MSH2 c.815C>T genes.
In triple negative MPN cases additional mutations were very rare. Two patients had germline mutations ANKRD26 c.2480T>C and RELN c.3651C>G and in one patient TET2 c.5152G>T was found.
Conclusion
In our study frequency of JAK2 and CALR mutations consisted 47% and 21%, respectively. Mutations in MPL gene were not observed. Thus, 32% patients were triple negative. The value of germline mutations in development of MPN should be further evaluated.
Session topic: 15. Myeloproliferative neoplasms – Biology & Translational Research
Keyword(s): Children, Mutation status, Myeloproliferative disorder
Abstract: PB2263
Type: Publication Only
Background
Myeloproliferative neoplasms (MPNs) are a group of clonal hematopoietic stem cell disorders, which are exceedingly rare and poorly understood in children. The reported frequency of JAK2 (V617F), MPL, CALR mutations is much lower in pediatric patients than in adults and the underlying genetics remain largely unknown.
Aims
The aim of our study was to characterize mutational profile of pediatric MPNs using next-generation sequencing (NGS).
Methods
The study included 19 patients diagnosed as Ph-negative MPN (11 boys and 8 girls). Essential thrombocythemia (ET) was diagnosed in 12 patients, polycythemia vera (PV) in 7 patients. The median manifestation age was 7.5 years (ranged from 3 months to 21 years).
Next-generation sequencing (NGS) was performed using MiSeq (Illumina, USA). Amplicon library was prepared using Human Myeloid Neoplasms Panel, № DHS-003Z (Qiagen, Germany), which included 141 genes. Fragment analysis of CALR gene exon 9 was performed for the detection of indels using ABI PRISM 3500 (Applied Biosystems).
Results
Classical JAK2(V617F) mutation was found in 9 patients: six patients with PV (86%) and two with ET (17%). Also JAK2 c.1613_1616delACAAinsT in exon 12 was found in one case with PV.
Mutations in CALR gene exon 9 were identified in four patients with ET (33%). Type 1 CALR frameshift mutation, a 52-bp del (p.L367fs*46) was found in two cases and one patient carried type 2 mutation, a 5-bp TTGTC insertion (p.K385fs*47), one patient harbored complex mutation c.1149-1154_delGGACAAinsTCCTTGTC(p.E383fs*48).
No additional somatic mutation in epigenetic regulators (ASXL1, IDH1/2, DMT3A) specific for adult MPN were observed in our group.
Investigation of 22 matched germline and somatic samples in 11 cases revealed the germline nature of the majority of additional mutation in epigenetic regulators (IDH2, TET2, EZH2, EP300, BCOR, CREBBP), in JAK-STAT negative regulators (SH2B3) and recurrent mismatch repair gene (MSH6), annotated as “possibly pathogenic” by predictive software.
One JAK2(V617F) positive PV patient carried germline mutation BLM c.1642C>T, which was described as the breast and prostate cancer predisposal mutation. This patient also had somatic mutation in BCOR c.4934C>G and MSH2 c.815C>T genes.
In triple negative MPN cases additional mutations were very rare. Two patients had germline mutations ANKRD26 c.2480T>C and RELN c.3651C>G and in one patient TET2 c.5152G>T was found.
Conclusion
In our study frequency of JAK2 and CALR mutations consisted 47% and 21%, respectively. Mutations in MPL gene were not observed. Thus, 32% patients were triple negative. The value of germline mutations in development of MPN should be further evaluated.
Session topic: 15. Myeloproliferative neoplasms – Biology & Translational Research
Keyword(s): Children, Mutation status, Myeloproliferative disorder