MLPA is a powerful tool for detecting lymphoblastic transformation in chronic myeloid leukemia and revealing the clonal origin of relapse in pediatric acute lymphoblastic leukemia.

Copy number alterations (CNAs) at 58 different loci have been investigated in 95 bone marrow or peripheral blood samples from patients with chronic myeloid leukemia (CML) or pediatric acute lymphoblastic leukemia (pALL) using multiplex ligation-dependent probe amplification (MLPA). In all but one case, the CNA profile correctly distinguished patients with CML who were in chronic phase from those in lymphoblast crisis. Within the chronic phase group, we could not separate patients resistant to imatinib therapy from those who were good responders. In our investigation of patients with pALL, a panel of MLPA probes broader than ever before was applied. Paired diagnostic and relapse samples from patients with pALL demonstrated clonally related or independent dominant clones, suggesting the presence of a pre-leukemic cell group. Identification of the origin of cell populations dominating at relapse will have a great effect on future treatment strategies. In summary, we have demonstrated the versatility of MLPA by using this cost-effective technique for two new applications.