[The role of TEL and AML1 genes in the pathogenesis of hematologic malignancies].

TEL and AML1 genes occur in a markedly high number of different aberrations in haematological malignancies. Besides the AML1, TEL is often fused to genes, which encod thyrosin-kinases. AML1 gene is a part of CBF transcription factor. AML1 can be altered in childhood acute lymphoblastic leukaemia (ALL) and also in a substantial number of acute myeloid leukaemias (most frequently as an AML1/ETO fusion). TEL/AML1 fusion gene (derived from t(12;21)(p13;q22) translocation) became recently one of the most important genetic aberrations in children with ALL. TEL/AML1 act presumably as dominant inhibitors of the second AML1 allele and thus they block transcription of genes dependent on CBF factor. Childhood ALL with TEL/AML1 hybrid gene is very frequent (approximately 22% of overall childhood ALL in the Czech Republic) and patients with this fusion form relatively homogenous group. These children are diagnosed mostly in pre-school age as a B cell precursor leukaemias and they have very good treatment results.