"Plasma cell myeloma (PCM) is an incurable malignancy. Cytogenetics, molecular genetics and single nucleotide polymorphism arrays have shown significant genetic complexity in PCM. However, these screens reflect only the predominant clonal population and genetic-based prognostic classification of PCM can predict the outcome only in a subset of cases. To better understand the oncogenesis of PCM combined investigation of genetic abnormalities at single cell level is needed.The original theory of clonal evolution in cancer proposed a stepwise, linear acquisition of mutations; however a branching sub-clonal genetic structure has recently been demonstrated in the leukaemia-propagating (‘stem’) cells of acute lymphoblastic leukaemia. The aim of this project is (i) to determine whether sub-clonal heterogeneity is a feature of PCM, (ii) to determine whether there is any particular order of acquisition of translocations, copy number alterations and gene mutations, (iii) to examine clonal heterogeneity with progression of disease and (iv) to determine whether myeloma propagating cells also show sub-clonal genetic heterogeneity.Purified plasma cells from patients with PCM as well as monoclonal gammopathy of undetermined significance and plasma cell leukaemia will be investigated. Specific abnormalities, identified by pre-screening tests, will be analyzed at single cell level using multicolour-FISH and a high-throughput microfluidic platform. Serial transplantation of malignant cells into NOD/SCID mice will be used for investigation of sub-clonal heterogeneity of myeloma propagating cells.We anticipate that this project will identify key mechanisms in myeloma progression potentially leading to the introduction of a much more precise prognostic classification and residual disease monitoring. If myeloma stem cells are genetically diverse, this offers the potential to alter treatment strategies and will have major implications for management of patients with PCM."