For instance, the acute promyelocytic leukemia (APL) with the classical M3 morphology needs to be confirmed by polymerase chain reaction (PCR) or fluorescent in-situ hybridization (FISH) for PML/RARA fusion gene and is treated with an all-trans retinoic acid based therapy [3], AML-M4Eo with inv(16)(p13q22) on the other hand is characterized by bone marrow eosinophilia and has a favorable prognosis [4]. This evidence concerns the gene RARA and acute promyelocytic leukemia.