NEW SHOWINGS OF 5Q- SYNDROME BASED ON SERIAL MEASUREMENTS OF BAALC-EXPRESSING STEM CELLS BURDEN IN BONE MARROW.

Abstract

Introduction: The 5q- deletion is macrocytic anemia syndrome with special clinical characteristics and relatively longer median survival with low probability of AML progression. The classification of this disease as MDS is still under debates. Molecular studies, such as tracking the leukemia-associated marker BAALC, may clarify this issue. Here we evaluated BAALC-expressing stem cells (BAALC-e SCs) in patient's with isolated 5q- syndrome and with different chromosomal abnormalities. Methods: The study includes analysis of bone marrow (BM) from 16 patients with isolated 5q deletion and 15 samples of 5q- combined with additional non-identical chromosomal abnormalities. BMs from 10 MDS patients without 5q- but carrying other cytogenetic aberrations were studied as control group. Serial measurements of BAALC-e SCs were performed by qPCR using BAALC RQ Kit (Inogene, Russia). Cytogenetic study included standard karyotyping and FISH. Results: The data analysis revealed that only 10% (2/16) of patients with isolated 5q- had BAALC gene overexpression. Further on, low BAALC-expressing stem cells were characteristic also in the group of 5q- combined with additional non-identical chromosomal aberrations (56%). Meanwhile, in control group this rate was higher (100%). Conclusions: The presented data of BAALC-e SCs burdens in patients with isolated 5q- syndrome indicate that this pathology differs from typical MDS and can be considered as ribosomopathy with low risk of transformation to MDS or AML. From this position, the biological advantages of 5q deletion syndrome are obvious as an optimal clinical model for further study of MDS and AML formation at the level of leukemia-initiating cells.