PML and acute promyelocytic leukemia: PML‐RARα FG is present in almost all APL cases and is a biomarker for APL diagnosis, disease burden, minimal residual disease (MRD) monitoring, and molecular remission.5, 6, 7 Detection methods for t(15;17) or PML‐RARα FG include conventional chromosome analysis, fluorescence in situ hybridization, and polymerase chain reaction (PCR).