Molecular Heterogeneity of Pediatric AML with Atypical Promyelocytes Accumulation in Children-A Single Center Experience.

Acute promyelocytic leukemia (APL) pathogenesis is based on gene translocations, which are of high importance in the diagnosis of and proper therapy selection for APL. However, in some cases acute myeloid leukemia (AML) demonstrates APL-like morphological features such as atypical promyelocytes accumulation. This type of AML is characterized by the involvement of other family members or completely different genes. In the present study, we used conventional karyotyping, FISH and high-throughput sequencing in a group of 271 de novo AML with atypical promyelocytes accumulation. Of those, 255 cases were shown to carry a typical chromosomal translocation t(15;17)(q24;q21) with chimeric gene formation (94.1%). Other -positive cases exhibited cryptic fusion without t(15;17)(q24;q21) (1.8%, = 5) and variant t(5;17)(q35;q21) translocation with chimeric gene formation (1.5%, = 4). However, 7 -negative AMLs with atypical promyelocytes accumulation were also discovered. These cases exhibited and fusions as well as mutations, e.g., insertion and non-recurrent chromosomal aberrations. Our findings demonstrate the genetic diversity of AML with APL-like morphological features, which is of high importance for successful therapy implementation.