Prevalence and clinicopathological features of driver gene mutations profile in BCR:ABL1 negative classical myeloproliferative neoplasm-A single-center study from North India

Background: Recurrent somatic mutations in the JAK2 , CALR , and the MPL genes are noted in BCR:ABL1 negative classic myeloproliferative neoplasms (MPN) that includes polycythemia vera (PV), essential thrombocytosis (ET), and primary myelofibrosis (PMF).

Materials and methods: Mutation profile and clinical features of MPN cases diagnosed at a tertiary care center in North India are being described. JAK2V617F mutation was screened using ARMS PCR, and CALR mutation was screened using allele-specific PCR followed by fragment analysis. MPL and JAK2 Exon 12 mutations were screened by Sanger sequencing. Some of the samples were also screened using commercial kits based on single-plex RT PCR.

Results: A total of 378 cases (including 124 PV, 121 ET, and 133 PMF cases) were screened over 6.5 years. JAK2V617F mutation was noted in 90.3%, 61.1%, and 69.2% of cases of PV, ET, and PMF, respectively. In PV, JAK2V617F wild-type cases were associated with a significantly lower age (44 yrs vs 54 yrs; P = 0.001), lower TLC (6.3 vs 16.9; P = 0.001), and a lower platelet count (188 × 109/L vs 435 × 109/L; P = 0.009) as compared to the JAK2V617F mutated cases. CALR and MPL mutations were noted in 17.4% and 12% and 0.8% and 5.3% of ET and PMF cases, respectively. Type 1 CALR mutations were commoner in both ET and PMF. The triple negative cases constituted 20.7% and 13.5% cases of ET and PMF, respectively. In ET, the triple negative cases were found to have a significantly lower median age of presentation (42 yrs vs 52 yrs; P = 0.001), lower median TLC (10.2 × 109/L vs 13.2 × 109/L; P = 0.024), and a higher median platelet count (1238 × 109/L vs 906 × 109/L; P = 0.001) as compared to driver genes mutated cases. In PMF, the triple negative cases were found to have a significantly lower hemoglobin level (7.9 g/dl vs 11.0 gl/dl; P = 0.001) and a significant female preponderance ( P = 0.05) as compared to the mutated cases. CALR mutations were found to have a significantly lower median age (43 yrs vs 56 yrs; P = 0.001) and lower hemoglobin (9.6 g/dl vs 11.3 g/dl) as compared to the JAK2 mutations.

Conclusion: Our data on the driver gene mutational profile of BCR:ABL1 negative MPN is one of the largest patient cohorts. The prevalence and clinicopathological features corroborate with that of other Asian studies.