FIP1L1-PDGFRA Gene Rearrangement by FISH Analysis in Pakistani Patients with Eosinophilia: Clinico-Haematologic Correlation

Objective: To detect FIP1L1-PDGFRα gene rearrangement using Fluorescence in situ hybridization (FISH) in patients with eosinophilia and correlate the clinicohaematologic features. Study design: Cross-sectional study. Place and Duration of Study: Haematology Department, Armed Forces Institute of Pathology, Rawalpindi Pakistan, from Jul 2016 to Jun 2017. Methodology: Patients having eosinophilia (absolute eosinophil count >1.5x109/l), both genders and any age group were recruited. Detailed history, signs and symptoms , blood counts and differential counts were recorded and peripheral films examined. FISH analysis was done for FIP1L1-PDGFRA gene rearrangement on peripheral blood/bone marrow samples using Metasystem XL PDGFRA probe. Results: Sixty patients were enrolled in our study. Mean age was 44.0±8.53 years. There were 49(81.7%) males and 11(18.3%)female patients. Absolute eosinophil count ranged from 4x109/l to 38x109/l with a mean of 21x109/l ±10.47x109/l. Thirty two (53.3%) patients had underlying myeloid neoplasm while 28(46.7%) had lymphoid neoplasm. PDGFRA gene re-arrangement was detected in 7(11.7%) patients. There was no statistically significant difference in the frequency of PDGFRA gene re-arrangement across age (p=0.758), gender (p=0.456), absolute eosinophil count (p=0.903) and underlying hematological disorder (p=0.830) groups. Conclusion: The PDGFRA gene re-arrangement was detected in 11.7% of patients, being more prevalent in Myeloid as compared to Lymphoid neoplasms.