Regarding the potential relationship between PML-RARA isoforms and various studied variables in Iranian APL patients, our results unveiled a significant association between bcr3 isoform and specific factors such as leukocytosis (high-risk group) and higher WBC count, a finding well-documented in numerous studies and reference texts (17, 18, 30, 35, 38). This evidence concerns the gene PML and Increased total leukocyte count.