- diagnosis of APL based on morphological grounds, and which will have to be confirmed by presence of t(15;17) and/or PML-RARα rearrangement (if RT-PCR for APL cannot be performed at your center, send fresh cells to Prof.C.Chomienne, Centre Hayem, Hopital St.Louis, 1 av. Claude Vellefaux, 75475 PARIS or keep frozen RNA [not frozen cells, as the RNA yield for PML-RAR is often poor in those cells]).