Predmetom tejto dizertačnej práce bolo určenie molekulárnych markerov, ktoré asociujú s prognózou akútnych myeloblastových leukémií (AML) a štúdium molekulárnej patogenézy chromozómových aberácií v oblasti ťažkého reťazca imunoglobulínu (IGH, 14q32.33), ktoré sú rekurentné u vybraných B - lymfoidných malignít.The object of this PhD thesis was to determine molecular markers that associate with the prognosis of acute myeloid leukaemia (AML) and to study the molecular pathogenesis of chromosomal aberrations involving the immunoglobulin heavy chain (IGH) at 14q32.33 that are recurrent in selected B - cell malignancies. In a cohort of AML with normal karyotype (NK-AML) we evaluated mutations in the NPM1, FLT3, CEBPA, IDH1, IDH2, WT1 and KMT2A genes and we analysed the therapeutic response in the context of the heterogeneous molecular background of the disease. Based on complex molecular profiling of mutations in NPM1, CEBPA and internal tandem duplications in FLT3 we have identified molecular subgroups with different clinical outcome and prognosis. More certain molecular heterogeneity became obvious when considering somatic mutations in IDH1/IDH2, WT1 and KMT2A genes. We assume that such complex and individually specific mutation interplay that hallmarks NK-AML genomes in our study may modify the prognosis of leukaemia in particular patients even after they are stratified to distinct molecular risk groups. In a group of B-cell malignancies with interstitial deletions of chromosome 14 involving IGH at 14q32.33 our data do not support the hypothesis of a putative tumor suppressor gene located in the imprinted region at 14q32 that would be repressed by targeted deletion of its active (paternal or maternal) allele. In another group of B-cell malignancies with villous lymphocytes characterized by t(14;14)(q32.13;q32.33) or inv(14)(q32.13q32.33) respectively we present data that argue against the hypothesis that the candidate long non-coding RNAs are deregulated due to chromosome 14 aberrations in the 14q32.13 / 14q32.33 region. The results of this PhD thesis are essential for the prognostic and therapeutic stratification of patients diagnosed and treated as NK-AML. The molecular genetic analyses performed in a group of B-cell malignancies contribute to the detailed characterization of chromosomal aberrations involving the IGH locus at 14q32.33.