3. INTRODUCTION
Sickle-cell disease (SCD) Also known as drepanocytosis.
hereditary blood disorder.
characterized by an abnormality in the oxygen-
carrying haemoglobin molecule in red blood cells. This results in sickle-
like shaped RBCs.
Associated with a number of acute and chronic health problems:
o severe infections, attacks of severe pain and
o stroke
o and increased risk of death.
4. Figure A shows normal red
blood cells flowing freely in a
blood vessel. The inset image
shows a cross-section of a normal
red blood cell with normal
hemoglobin. Figure B shows
abnormal, sickled red blood cells
blocking blood flow in a blood
vessel. The inset image shows a
cross-section of a sickle cell with
abnormal (sickle) hemoglobin
forming abnormal strands.
5. S I C K L E - C E L L S I N H U M A N B L O O D : B O T H N O R M A L
R E D B L O O D C E L L S A N D S I C K L E - S H A P E D C E L L S
A R E P R E S E N T.
6. N O R M A L B L O O D C E L L S N E X T T O A S I C K L E - B L O O D
C E L L , C O L O R E D S C A N N I N G E L E C T R O N M I C R O S C O P E
I M A G E
7. CAUSE
Occurs when a person inherits two abnormal copies of the
haemoglobin gene, one from each parent.
Several subtypes exist, depending on the exact mutation in each
haemoglobin gene.
A person with a single abnormal copy does not experience
symptoms and is said to have sickle-cell trait.
8. Normally, humans have haemoglobin A, which consists of two
alpha and two beta chains.
The gene defect is a known mutation of a
single nucleotide ( single-nucleotide polymorphism - SNP ) of the β-
globin gene, which results in glutamic acid being substituted
by valine at position 6.
9. GENETICS
Sickle-cell conditions have an autosomal recessive pattern of inheritance
from parents.
The types of haemoglobin a person blood acquires depend on what
haemoglobin genes are present in her or his parents.
If one parent has sickle-cell anaemia and the other has sickle-cell trait,
then the child has a 50% chance of having sickle-cell disease and a 50%
chance of having sickle-cell trait.
When both parents have sickle-cell trait, a child has a 25% chance of
sickle-cell disease, 25% will not carry any sickle-cell alleles, and 50% will have
the heterozygous condition
10.
11.
12. PATHOPHYSIOLOGY
Normal red blood cells are quite elastic, which allows the cells to deform
to pass through capillaries.
In sickle-cell disease, the low-oxygen tension promotes red blood cell
sickling.
Repeated sickling damages the cell membrane and decrease the cell's
elasticity.
As a consequence, these rigid blood cells are unable to deform as they
pass through narrow capillaries, leading to vessel occlusion and ischaemia.
13. SIGNS AND SYMPTOMS
Sickle-cell disease may lead to various acute and chronic
complications, several of which have a high mortality rate.
Sickle-cell crisis- Results in Anemia
Vaso-occlusive crisis- Restrict blood flow : ischaemia
Acute chest syndrome- Dyspnea (breathlessness)
Haemolytic crisis- accelerated drops in haemoglobin level
14. DIAGNOSIS
Hemoglobin values of
Normal Adult: 13.5 - 17 g/dl
Affected person: range of 6–8 g/dl
Detected by haemoglobin electrophoresis.
The diagnosis can be confirmed with high-performance liquid
chromatography.
Neonatal screening is done for early detection of individuals with sickle-
cell disease, but also allows for identification of the groups of people that carry
the sickle cell trait.
15. TREATMENT AND
MANAGEMENT
Folic acid and penicillin- 1 mg dose of folic acid daily for life.
Penicillin intake due to the immature immune system
Hydroxyurea- Decrease the number and severity of attacks
Transfusion therapy- Addition of normal red blood cells
Bone marrow transplants
16. DID YOU KNOW??
Almost 300,000 children are born with a form of
sickle-cell disease every year, mostly in sub-
Saharan Africa, but also in other countries such
as the West Indies and South Asia, and
in people of African origin elsewhere in the
world.
17. D I S T R I B U T I O N O F T H E S I C K L E - C E L L T R A I T S H O W N
I N P I N K A N D P U R P L E
