Acute Leukaemia Flashcards
What are the main features of acute leukaemia (5)
A neoplastic condition characterised by: Rapid onset Early death if untreated Immature cells (blast cells) Bone marrow failure
What are the clinical signs of bone marrow failure (3)
Anaemia: fatigue, pallor, breathlessness
Neutropenia: infections
Thrombocytopenia: bleeding
Where cell do all blood cells originate
Pluripotent haemopoietic stem cell in the bone marrow
What are the main cell types (8)
Erythroid lineage Megakaryocyte lineage Neutrophil lineage Monocyte lineage Eosinophil lineage Basophil lineage B cells T cells
What cells are affected in chronic lymphoblastic leukaemia
B cells
What cells are affected in acute lymphoblastic leukaemia
T cell precursors (T-ALL)
B cell precursors (B-ALL)
What cells are affected in chronic myeloid leukaemia
Pluripotent haemopoietic stem cells
What cells are affected in acute myeloid leukaemia
Multipotent myeloid stem cell/progenitor cell
What is the dominant cell type in acute leukaemias
Blast cells
Demographics of AML (3)
Increases with age
Prognosis worse with increasing age
40% of adults cured
What are the chromosomal abnormalities that lead to leukaemias (5)
Duplication (usually trisomy) Loss Translocation Inversion Deletion
What are the chromosomal translocations in AML (2)
T(15;17)
T(5;8)
What is the chromosomal inversion in AML
Inv(16)
What leukaemias tend to have new fusion genes (2)
AML
ALL
What leukaemia tends to have abnormal regulation of genes
ALL
What leukaemia can have chromosomal duplication
AML
What are hotspot chromosomes for duplication in AML (2)
+8
+21
Dosage effect - extra copies of proto-oncogenes
What leukaemia can have chromosomal loss or deletion
AML
What are chromosomal hotspots for loss/deletion in leukaemia (2)
5/5q
7/7q
How can chromosomal loss/deletion cause leukaemia (3)
Possible loss of tumour suppressor genes
Or…one copy of an allele may be insufficient for normal haemopoiesis
Possible loss of DNA repair systems
What molecular abnormalities can occur in leukaemia (4)
Point mutation - NPM1, CEBPA
Loss of tumour suppressor genes
Partial duplication - FLT3
Cryptic deletion
What effect does partial duplication of FLT3 have in leukaemia
Proliferation and survival effects
What is the pathogenesis of most AML
Block of maturation of granulocyte
Accumulation of blast cells
What is the characteristic cell of leukaemia
Blast cells
What are the risk factors for AML (5)
Familial or constitutional predisposition Irradiation Anticancer drugs Cigarette smoking Unknown
What is the characteristic of leukaemogenesis in AML
Multiple genetic hits:
At least 2 interacting molecular defects synergise to give leukaemic phenotype
What two abnormalities occur in leukaemogenesis in AML (2)
Type 1 abnormalities - promote proliferation and survival
Type 2 abnormalities - block differentiation (which would normally be followed by apoptosis)
How is cell differentiation mediated
Transcription factors:
Bind to DNA
Alter structure to favour transcription
Regulate gene expression
If transcription factor function is disrupted, cells cannot differentiate
What proteins are involved in cell differentiation
Core binding factor:
Dimeric transcription factor
Master controller of haematopoiesis
What core binding factor abnormalities cause AML (2)
T(8;21) fuses RUNX1 (encoding CBFalpha) with RUNX1T1 - 15% of adult AML
Inv(16) fuses CBFB with MYH11 - 12% of adult AML
What is the histology in t(8;21) AML (2)
Some blast cells
Some mature cells
What is the histology in Inv(16), t(16;16)
Some maturation to bizzarre eosinophil precursors with giant purple granules
What is important about t(15;17) acute promyelocytic leukaemia (8)
A very special type of acute leukaemia
The molecular mechanism is understood
Molecular treatment can be applied
The great majority of patients can now be cured
An excess of abnormal promyelocytes
Disseminated intravascular coagulation (DIC)
Two morphological variants but the same disease
When is maturation blocked in t(15;17) AML
Later than in other AML
What are the leukaemogenesis abnormalities in acute promuelocytic leukaemia (2)
Type 1 abnormalities - FLT3-ITD
Type 2 abnormalities - t(15;17) PML-RARA
What are the leukaemogenesis abnormalities in CBF leukaemias (2)
Type 1 abnormalities - sometimes mutated KIT
Type 2 abnormalities - mutation affecting function of CBF