Transcript CHIMERISM. Principles and practise.

Normal haemopoiesis
ABNORMALITIES IN THE
HEMOPOIETIC SYSTEM
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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
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6
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8
13
14
19
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9
15
21
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22
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x
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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
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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
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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