Clinic Study On Expression Of JAK2 And MPL Mutations In Patients With Chronic Myeloproliferative Diseases

Background and ObjectiveRecent researches suggest that JAK2V617F and MPLW515L/K have great correlation with typical CMPD,JAK2V617F mutation was identified in most of PV patients and about half of ET patients,while MPLW515 mutation was just found in a few patients of IMF.These mutations play important role in CMPD's pathogenesis and diagnosis,in order to clarify the frequency and some clinical significance of JAK2V617F and MPLW515 mutation in the Chinese patients with CMPD and the patients with suspected "early MPD",we investigated these mutations in large sample of patients with three typical CMPD and 30 patients with slightly increased platelets or hemoglobin without secondary cause,who did not meet the criteria of polycythemia vera or essential thrombocythemia.MethordsIn the frist part of the study,we evaluated 314 Chinese patients with CMPD:170 with ET,110 with PV,and 34 with IMF.All of these patients were admitted to our hospital between April 2000 and February 2008.In 229 patients,genomic DNA was extracted from fresh bone marrow mononuclear cells(BMMCs).In other 85 patients, genomic DNA was extracted from methanol/acetic acid-fixed cells that had been routinely prepared for cytogenetic analysis.Allele-specific PCR and sequencing of JAK2 exon 12 was performed.Amplicons were size fractioned by standard agarose gel electrophoresis.Direct sequencing of PCR products was performed in selected patients.In the second part of the study,we investigated the MPLW515 mutation in 129 JAK2V617F-nagetive patients:80 with ET,33 with PV,and 16 with IMF.Genomic DNA was extracted from fresh bone marrow mononuclear cells(BMMCs).PCR and sequencing of MPL exon 10 was performed.Amplicons were size fractioned by standard agarose gel electrophoresis.Direct sequencing of PCR products was performed in selected patients.In the third part of the study,the prevalence of JAK2V617F in 30 patients with slightly increased platelets or hemoglobin without a secondary cause,who did not meet the criteria of polycythemia vera or essential thrombocythemia was carried out.The methord as the same as part one.And followed up the disease duration.ResultsWe identified heterozygous JAK2V617F mutation in 77/110(70%)patients with PV,90/170(52.94%)patients with ET,and 18/34(52.94%)patients with IMF, respectively.None of 129 JAK2V617F-nagetive patients has the MPLW515 mutation,this finding should be validated with much more sample.14 out of 30 patients(46.7%)were positive for the JAK2V617F mutation,and none of them had the MPLW515L/K.Five of these 14 patients had a history of thrombosis.All the patients have been followed up since onset.Refered to 22 available results,12 patients with the burden of JAK2V617F turned out to be MPD;only 2 out of 10 patients without this mutation also evolved to MPD.conclusionOur findings suggest that the JAK2V617F mutation is observed in Chinese patients with the classic CMPD with a significant percentage.The MPLW515 mutation's prevalence was lower than the reports from abroad,need enlarg sample to verification our finding.JAK2V617F mutation also occurs in a certain percentage of those patients with slightly increased platelets or hemoglobin,and has great significance to diagnose early MPD.