Sickle Cell Anemia

Sickle Cell Anemia

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  CURRENT AFFAIRS 2015 GROUP4 Esther and Nidhya IInd Sem B.sc Microbiology
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  SICKLE CELL ANEMIA Doneby group 4 Nidhya and Esther
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  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.
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   Figure Ashows 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.
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  S I CK 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.
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  N O RM 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
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  CAUSE  Occurs whena 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.
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   Normally, humanshave 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.
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  GENETICS  Sickle-cell conditionshave 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
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  PATHOPHYSIOLOGY  Normal redblood 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.
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  SIGNS AND SYMPTOMS Sickle-celldisease 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
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  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.
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  TREATMENT AND MANAGEMENT  Folicacid 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
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  DID YOU KNOW?? Almost300,000 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.
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  D I ST 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
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  Thank you