[A quantitative assay for JAK2 mutation in 135 patients with chronic myeloproliferative neoplasms].

Objective: To investigate the frequency and mutational status of JAK2 mutation in Chinese patients with chronic myeloproliferative neoplasms (MPN) and study the relative quantitation and clinical implications of mutated JAK2 transcript.

Methods: JAK2 mutation and the mutational status were screened with amplification-refractory mutation sequencing polymerase chain reaction (ARMS-PCR), the relative quantity of mutated JAK2 mRNA by using capillary electrophoresis.

Results: JAK2V617F mutation was detected in 95 of 135 MPN patients, including 37 (97.4%) of 38 polycythemia vera (PV), 56 (59.6%) of 94 essential thrombocythemia (ET) and 2 of 3 idiopathic myelofibrosis (IMF) patients; the difference between the mutations in PV and ET was significant (P<0.05). Of 95 JAK2V617F patients examined, 18/38 PV patients (47.3%) and 17/94 (18.1%) ET patients and 1 IMF patient were homozygotes, and ET patients showed lower prevalence of homozygote (P<0.05). In 95 MPN patients, the mutated mRNA ratio was higher in homozygote than in heterozygote patients. PV heterozygote patients showed higher levels of mutated JAK2 mRNA than ET heterozygote patients (P<0.05). The levels of JAK2V617F mRNA in patients over 60 years of age were significantly higher than that in those less than 60 years of age (P<0.001). Higher leukocyte counts were observed in PV and ET patients with higher levels of mutated JAK2 mRNA (P<0.05). The presence of JAK2V617F was found to be significantly associated with higher hemoglobin level in ET patients. Cytogenetic analysis was performed in 101 of the 135 patients, the association between abnormal karyotype and JAK2V617F was not found.

Conclusion: The ARMS-PCR technique can be used to detect the frequency and mutational status of JAK2V617F mutation, and along with capillary electrophoresis, the estimation of minimal residual disease becomes possible.