VastmajorityofcasesofAcute Promyelocytic Leukemia (APL) have a translocation t(15;17)(q22;q12-21) which fusesthePromyelocyticgene(PML)on chromosomeband15q22totheRetinoic acidreceptoralpha(RARA)geneat 17q12-21.ThisPML/RARAfusionis associatedwithagoodresponsetoall- transretinoicacidtherapy.