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Normal haemopoiesis ABNORMALITIES IN THE HEMOPOIETIC SYSTEM • • • • CAN LEAD TO HEMOGLOBINOPATHIES HEMOPHILIA DEFECTS IN HEMOSTASIS/THROMBOSIS • HEMATOLOGICAL MALIGNANCY MUTATIONS AND DNA • VARIOUS TYPES OF MUTATIONS CAN OCCUR LEADING TO DISEASE PHENOTYPE • POINT MUTATIONS • INSERTIONS OR DELETIONS • TRANSLOCATIONS • COMPLEX CHROMOSOMAL REARRANGEMENTS EXAMPLE OF COMMON MUTATIONS IN HUMAN DISEASE Sickle cell disease Sickle cell disease, morphology and molecular VARIABILITY IN GENETIC DISEASES •ONE DISEASE, ONE GENE, ONE MUTATION •ONE DISEASE, ONE GENE, MANY MUTATIONS •ONE DISEASE, MORE THAN ONE GENE, MANY •MUTATIONS HAEMOPHILIA X LINKED RECESSIVE DISORDER HAEMOPHILIA A – MUTATIONS IN FACTOR VIII GENE HAEMOPHILIA B – MUTATIONS IN FACTOR IX GENE SIMPLE AND COMPLICATED MUTATIONS THE FLIP TIP MUTATION F8B A E1 E22 E23 E26 CEN TEL F8A B TEL E1 E22 E23 E26 CEN F8A C E22 E1 E23 E26 TEL CEN INVERSION 22 FIGURE 4 THE IVS 22 MUTATION IN HAEMOPHILIA A. Genetic factors and deep vein thrombosis • FACTOR V LEIDEN MUTATION • PROTHROMBIN MUTATION • ? OTHER FACTORS IN THE PROTEIN C PATHWAY • FVL LEADS TO SIGNIFICANT INCREASE IN RISK OF DVT, PARTICULARLY IN ASSOCIATION WITH OTHER ENVIRONMENTAL FACTORS EG OCP CANCER DEVELOPMENT: ITS IN THE GENES HOW DOES A CELL BECOME TUMORIGENIC? • THREE PROCESSES ARE INVOLVED • IMMORTALISATION • TRANSFORMATION • METASTASIS IMMORTALISATION • PROCESS BY WHICH THE CELLS ARE INDUCED TO GROW INDEFINITELY TRANSFORMATION • CELLS ARE NOT CONSTRAINED IN TERMS OF GROWTH CHARACTERISTICS AND TEND TO BECOME FACTOR INDEPENDENT METASTASIS • CANCER CELLS GAIN THE ABILITY TO INVADE NORMAL TISSUE AND ESTABLISH OTHER FOCI OF MALIGNANCY WHAT CAUSES CELL TRANSFORMATION? • ENVIRONMENTAL • CARCINOGENS(INITIATORS AND PROMOTERS) • GENETIC • SOMATIC MUTATIONS • MENDELIAN INHERITANCE ONCOGENES • NORMAL CELLULAR COUNTERPARTS(PROTOONCOGENES) • MUTATION/ACTIVATION LEADS TO TUMOR FORMATION • HUNDREDS OF ONCOGENES IDENTIFIED • GAIN OF FUNCTION Tumour suppressor genes • Originally known as recessive oncogenes • Need to have both copies of the gene affected to promote a malignant phenotype • Knudsons 2 hit hypothesis • First mutation makes cells susceptiple to development of cancer • 2nd hit leads to a malignant phenotype TRANSLOCATIONS AND CANCER • SEEMS PARTICULARLY RELEVANT IN HEMATOLOGICAL MALIGNANCIES • CHRONIC MYELOID LEUKEMIA • ACUTE PROMYELOCYTIC LEUKEMIA • BURKITTS LYMPHOMA • NON HODGKINS LYMPHOMA Leukaemia, the current hypothesis • Defect in maturation of white blood cells • May involve a block in differentiation and/or a block in apoptosis • Acquired genetic defect • Initiating events unclear • Transformation events involve acquired genetic changes • Chromosomal translocation implicated in many forms of leukaemia Chronic Myeloid Leukaemia • Malignancy of the haemopoietic system • Transformation of the pluripotent stem cell • 9;22 translocation giving rise to the Philadelphia (Ph’) chromosome • Creation of a leukaemia specific mRNA (BCRABL) • Resistance to apoptosis, abnormal signalling and adhesion • Molecular diagnostics • Molecular and cellular therapeutics Cytogenetic Abnormality of CML: The Ph Chromosome 1 6 2 7 3 8 13 14 19 20 4 9 15 21 5 10 16 22 11 17 x 12 18 Y The Ph Chromosome: t(9;22) Translocation 9 9 q+ 22 Ph ( or 22q-) bcr bcr-abl abl FUSION PROTEIN WITH TYROSINE KINASE ACTIVITY Prevalence of the Ph Chromosome in Haematological Malignancies Leukaemia % of Ph+ Patients CML 95 ALL (Adult) 15–30 ALL (Paediatric) 5 AML 2 Faderl S et al. Oncology (Huntingt). 1999;13:169-184. bcr-abl Gene and Fusion Protein Tyrosine Kinases Chromosome 22 Chromosome 9 c-bcr 1 2-11 c-abl p210Bcr-Abl 2-11 2-11 p185Bcr-Abl Exons Introns CML Breakpoints ALL Breakpoints Adapted from Melo JV. Blood. 1996;88:2375-2384. NON HODGKINS LYMPHOMA • B CELL FOLLICULAR LYMPHOMA • t(14;18)(q21;q14) • BCL 2 AND IMMUNOGLOBULIN GENES INVOLVED • DYSREGULATION OF BCL 2 • FAILURE OF APOPTOSIS Detecting Cancer – where to begin? Detecting cancer, the need for a marker of disease Detecting Cancer – different markers for different diseases? Cancer Molecular Diagnostics – discriminating cancers at the gene level How Cancer Molecular Diagnostics? • Chromosome analysis • Gene analysis • Gene expression analysis • Protein analysis • Gene chip analysis Leukaemia diagnostics • • • • • Morphology Cytogenetics Fluorescent In Situ Hybridisation (FISH) Immunophenotyping PCR of chromosomal translocations New developments in Cancer Molecular Diagnostics The Gene Chip The Gene Chip, a Molecular snap shot of the cell MOLECULAR MEDICINE • • • • • A new approach to medicine New Diagnostics New Therapeutics A number of agents now in clinical trials Molecular medicine will help identify new targets and permit rational drug development