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Molecular Hematology
Galila Zaher
DNA
RNA
Protein
DNA & RNA
DNA
Double-stranded
4 bases: A, C, G & T
Sugar: Deoxribose
Stable molecule
Introns + Exons
RNA
Single-stranded
A, C, G & U
Sugar: Ribose
Unstable molecule
Introns
DNA: Building Blocks
Bases
Purines
Pyrimidine
Purine
Pyrimidines
Adenine
Guanine
Cytosine
Thymine
[Uracil]
Purine ‘pair’ pyrimidine
Adenine-Thymine
Guanine-Cytosine
DNA
Nature paper here
Chromosomes
Male
karyotype
46:XY
Female
karyotype
46:XX
22 pairs of autosomes + 1 pair sex chromosomes
Normal Structure
 Somatic cell has 46 chromosomes : diploid.
 Ova and sperm have 23 chromosomes :haploid.
 Karyotype shows chromosomes of dividing cell in
numerical order.
 Chromosome has two arms:
 Short arm = p
 Long arm = q.
 Short and long arms meet
at the Centromere.
 Ends of the chromosomes
are called Telomeres
 Each arm is divided into
regions numbered from
centromere.
 Each region is divided into
bands.
Numerical Abnormality
Aneuploid: Somatic cell with >or <46
chromosomes
A. Hyperdiploid: >46 chromosomes
B. Hypodiploid : <46 chromosomes.
 Pseudodiploid: 46 chromosomes but with
rearrangements.

Structural Abnormality
 del : deletion where part of chromosome is lost del(16q).
 Add: additional material has replaced part of a Ch
 t: Translocation t(9; 22)
 inv :inversion; part of Ch runs in opposite direction.
 Point mutation
 Non sense :Result in creation of premature stop codon
Normal sequence ATG CTG TGC  Cys
Mutant sequence ATG CTG TGA stop
 i: isochromosome is a chromosome with identical
chromosome arms at each end, e.g. i(17q) has two copies of
17q joined at centromere.
Haematological Malignancies
 Mostly clonal disorders resulting from a genetic
alteration.
 Tumor-Suppressor Genes : inhibit expression of
tumor phenotype. When are inactivated or lost 
abnormal proliferation
 Oncogenes :Genes which can potentially induce
neoplastic transformation. They include genes for
growth factors, growth factor receptors, protein
kinases,etc.
Genetics of Haematological
Malignancies
Mutation
Proto-oncogene
Normal proliferation / Apoptosis
Tumour-suppressor
gene
Oncogene
Excess proliferation
/ loss of Apoptosis
Mutation or deletion
Tumour-suppressor
gene
Clonal Progression
 Activation of Oncogenes
 Inactivation of Tumour-Suppressor Genes
 Malignant cells acquire new characteristics
causing acceleration.
 Multidrug resistance (MDR) is one
complication. Cells start to express a protein
which actively pumps chemotherapeutic agent
to outside of cells.
Thalassemia



1.
2.
3.

Heterogenous group of genetic disorders
Mutation decrease rate of synthesis of globin chains ( or ).
0 :complete absence of  chain . Common in Mediterranean.
+ :partial block in  chain synthesis.
Noncoding introns inefficient RNA splicing ,decreased mRNA
production
Promoter leading to decreased expression
Termination site production of longer, unstable mRNA
Partial or total deletion of a globin gene
 thalassemia major :0/0, +/ +, or 0/ +
ß-Thalassemias
 Disease manifests itself when switch    chain ms after





birth
Imbalanced synthesis  low Hb production, MCV & MCH
Excess  chains precipitate in RBC precursors in bone
marrow leading to hemolysis and ineffective erythropoiesis
Excess  chains in circulating RBCs precipitate leading to
pitting in spleen & RBC survival via a chronic hemolytic
process.
The major cause of severe anemia is the ineffective
erythropoiesis.
Compensatory increase in  &  chain synthesis  Hb F& A2.
Hereditary thrombophilia
 PC
 PS
 AT
 Prothrombin Gene Mutation:G20210A.
 Factor V Leiden Mutation: R506Q.
 MTRFR :mutation
INHERITED RISK FACTORS
Relative risk of VTE
50- to 80fold
80
70
60
50
40
30
20
10-fold
10- fold
5- to 8fold
2-to 4- fold
0
Heterozygous
deficiency of AT,
PC, PS
Heterozygous
G1691A FV
Homozyougs
G1691A FV
Heterozygous
G20210
prothrombin
Homozyg
prothrombin
Gene Structure
Splice sites
X-linked Disorders
 Haemophilia A and B
 X-linked disorders
 Males affected –
females carriers
Queen Victoria (1819 - 1901)
Queen Victoria Queen of
England from 1837 to
1901 was a carrier.
Her eighth child, Leopold,
had Hemophilia and
suffered from frequent
hemorrhage.
Royal Disease
Descendants Eugenie, who was a carrier introduced
Hemophilia into Spanish royal family .
Irene married to Prince Henry of Prussia introduced
the disease into the German royal family
Alexandra married Russia's last czar Nicholas II
introduced the disease into the Russia royal family,
which ultimately played a role in the start of the
Russian Revolution.
Alexis, son of Nicholas and
Alexandra (1904 - 1918)
Alexandra gave birth to a son Alexis
the long awaited heir Russian throne.
Unfortunately Alexis had Hemophilia
which ultimately played a role in the
start
of the Russian Revolution.
Victoria will be remembered as the
cause of Hemophilia which spread to
the Royal Family of Europe through
her descendants
F8 Gene
FIX Gene
Types of Mutations
 Missense mutations
 Nonsense mutations
 Splice mutations
 Insertions
 Deletions
Inversions Sever HA
SHA:
Intron 22:
Intron 1:
~50% cases
<1% cases
Haemophilia A: Intron 22
Inversion
Cytogenetic &Molecular
studies
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•
•
•
•
•
Karyotype Analysis (numerical )
Immunofluorescence Staining (structural)
Fluorescent in situ Hybridisation (FISH)
Southern Blot Analysis
Polymerase Chain Reaction (PCR)
t(9,22),hemophilia,thrombophilia
DNA Microarray Platforms
Chromosomes
Male
karyotype
46:XY
Female
karyotype
46:XX
22 pairs of autosomes + 1 pair sex chromosomes