Part I: View of cell origin, biology and genomic changes of leukaemic clone B-cell chronic lymphocytic leukaemia represents most common leukaemia in everyday praxis of internists and haematologists. New findings about tumour cell biology, lymphomagenesis research and description of different IgVH genes mutational status allow us to view the chronic lymphocytic leukaemia as a biologically heterogeneous disease with minimally two distinct subtypes arising from antigen-experienced mature B-lymphocyte. Detailed analysis of genetic aberrations, gene expression levels, cell proteins and surface antigens, understanding of tumour cells – bone marrow and lymphatic organs microenvironment interactions can reveal high-risk and poor prognosis patients in early disease phase and contribute to development of more effective and targeted therapy of B-cell chronic lymphocytic leukaemia in near future.

        Key words: B-cell chronic lymphocytic leukaemia, lymphomagenesis, IgVH mutation, genetic changes