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Questions and Answers
In sickle cell anemia, the substitution of valine for glutamate at the 6th amino acid position leads to a cascade of pathophysiological events. Which of the following is the MOST direct consequence of this substitution at the molecular level?
In sickle cell anemia, the substitution of valine for glutamate at the 6th amino acid position leads to a cascade of pathophysiological events. Which of the following is the MOST direct consequence of this substitution at the molecular level?
- Increased solubility of deoxyhemoglobin, facilitating enhanced oxygen carrying capacity under hypoxic conditions.
- Polymerization of deoxyhemoglobin molecules, leading to erythrocyte rigidity and sickling. (correct)
- Decreased affinity of hemoglobin for 2,3-diphosphoglycerate (2,3-DPG), resulting in a rightward shift of the oxygen dissociation curve.
- Enhanced binding of hemoglobin to carbon monoxide, exacerbating tissue hypoxia.
A patient with sickle cell anemia experiences vaso-occlusive crises. What is the MOST likely underlying mechanism contributing to these painful episodes?
A patient with sickle cell anemia experiences vaso-occlusive crises. What is the MOST likely underlying mechanism contributing to these painful episodes?
- Reduced levels of nitric oxide (NO) bioavailability, leading to impaired vasodilation and increased platelet aggregation.
- Increased production of erythropoietin leading to hyperviscosity and impaired microcirculation.
- Hyperactivation of the complement system, resulting in systemic inflammation and vascular damage.
- Adherence of sickled erythrocytes to the endothelium, obstructing blood flow and causing distal ischemia. (correct)
Splenic sequestration crisis is a serious complication of sickle cell anemia. Which of the following pathophysiological processes is MOST directly responsible for the rapid decrease in hemoglobin levels observed during this crisis?
Splenic sequestration crisis is a serious complication of sickle cell anemia. Which of the following pathophysiological processes is MOST directly responsible for the rapid decrease in hemoglobin levels observed during this crisis?
- Auto-splenectomy.
- Intravascular hemolysis caused by complement activation on abnormal red blood cells.
- Pooling of large numbers of sickled erythrocytes in the spleen, leading to a sudden drop in circulating red cell mass. (correct)
- Decreased erythropoiesis secondary to inflammatory cytokines released during the acute event.
A researcher is investigating novel therapeutic targets for sickle cell anemia. Which of the following approaches would MOST effectively address the root cause of erythrocyte sickling?
A researcher is investigating novel therapeutic targets for sickle cell anemia. Which of the following approaches would MOST effectively address the root cause of erythrocyte sickling?
A patient with sickle cell anemia presents with acute chest syndrome (ACS). Which of the following is the MOST critical initial step in managing this life-threatening complication?
A patient with sickle cell anemia presents with acute chest syndrome (ACS). Which of the following is the MOST critical initial step in managing this life-threatening complication?
A hematologist is evaluating the efficacy of hydroxyurea therapy in a patient with sickle cell anemia. Which of the following laboratory parameters would be the MOST indicative of a positive response to this medication?
A hematologist is evaluating the efficacy of hydroxyurea therapy in a patient with sickle cell anemia. Which of the following laboratory parameters would be the MOST indicative of a positive response to this medication?
Which of the following statements BEST describes the role of endothelial dysfunction in the pathophysiology of sickle cell anemia?
Which of the following statements BEST describes the role of endothelial dysfunction in the pathophysiology of sickle cell anemia?
A researcher aims to develop a novel point-of-care diagnostic test for sickle cell anemia. Which biophysical property of sickle hemoglobin (HbS) would be MOST appropriate to target for rapid and accurate detection?
A researcher aims to develop a novel point-of-care diagnostic test for sickle cell anemia. Which biophysical property of sickle hemoglobin (HbS) would be MOST appropriate to target for rapid and accurate detection?
A patient with sickle cell trait (HbAS) is undergoing genetic counseling. What is the probability that their child will have sickle cell anemia if their partner is also a carrier of sickle cell trait?
A patient with sickle cell trait (HbAS) is undergoing genetic counseling. What is the probability that their child will have sickle cell anemia if their partner is also a carrier of sickle cell trait?
A child with sickle cell anemia experiences frequent vaso-occlusive crises. Which of the following interventions has been shown to MOST effectively reduce the frequency and severity of these crises?
A child with sickle cell anemia experiences frequent vaso-occlusive crises. Which of the following interventions has been shown to MOST effectively reduce the frequency and severity of these crises?
What is the underlying mechanism by which autosplenectomy occurs in individuals with sickle cell anemia?
What is the underlying mechanism by which autosplenectomy occurs in individuals with sickle cell anemia?
A patient with sickle cell disease is screened via electrophoresis. With what percentage of HbS would this patient most likely present?
A patient with sickle cell disease is screened via electrophoresis. With what percentage of HbS would this patient most likely present?
What relevance does sickling have to normal RBCs?
What relevance does sickling have to normal RBCs?
Although Sickle Cell Anemia originated in Greece, India, and the Middle East, what is one benefit to contracting the disease?
Although Sickle Cell Anemia originated in Greece, India, and the Middle East, what is one benefit to contracting the disease?
What is occurring in the body that directly correlates to excessive de-oxygenation of RBCs?
What is occurring in the body that directly correlates to excessive de-oxygenation of RBCs?
A child who is a homozygote for Sickle Cell presents with HbS at 90% levels, and HbF at 5-10%. What does this indicate?
A child who is a homozygote for Sickle Cell presents with HbS at 90% levels, and HbF at 5-10%. What does this indicate?
What is the typical Hb level for a patient with Sickle Cell?
What is the typical Hb level for a patient with Sickle Cell?
When performing electrophoresis on a blood sample of a suspected Sickle Cell patient, what are the values we would expect to see?
When performing electrophoresis on a blood sample of a suspected Sickle Cell patient, what are the values we would expect to see?
What is Sodium metabisulfite used for when testing for Sickle Cell?
What is Sodium metabisulfite used for when testing for Sickle Cell?
When completing a solubility test on a blood sample, and the blood is less soluble than usual, what additive would be used?
When completing a solubility test on a blood sample, and the blood is less soluble than usual, what additive would be used?
Flashcards
Origin of Sickle Cell Anemia
Origin of Sickle Cell Anemia
Greece, India, Middle East (protects against malaria)
Sickle Cell Mutation
Sickle Cell Mutation
Glutamic acid is mutated to valine at the 6th amino acid position.
Pathophysiology
Pathophysiology
Polymerization of HbS leads to decreased RBC elasticity, causing cells to become stuck and unable to deform in narrow capillaries, leading to destruction in the spleen.
Sickle Cell Anemia Symptoms
Sickle Cell Anemia Symptoms
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Cause of Anemia
Cause of Anemia
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Splenic Infarction
Splenic Infarction
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Sickle Crisis
Sickle Crisis
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Homozygous HbS
Homozygous HbS
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Hemoglobin levels
Hemoglobin levels
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Peripheral Blood Smear Findings
Peripheral Blood Smear Findings
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Electrophoresis findings
Electrophoresis findings
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Treatment of Sickle Cell Anemia
Treatment of Sickle Cell Anemia
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Inheritance Pattern
Inheritance Pattern
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Heterozygote
Heterozygote
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Sickling Test
Sickling Test
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Solubility Test
Solubility Test
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Electrophoresis in Heterozygotes
Electrophoresis in Heterozygotes
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Study Notes
- Sickle Cell Anemia
Origin
- Greece, India, Middle East
- It protects against malaria
Mutation
- Glu -> Valine @ 17th base, 6th amino acid
- Negative -> neutral
- The chain easily precipitates upon O2
- α2β2 (low O2 tension) -> tetramers -> to O2 -> back to normal
- Eventually, it causes a loss of RBC elasticity (stuck) -> unable to deform in the narrow cap
Narrow Cap
- Destruction occurs in the spleen and vessel occlusion
- It causes ischemia
Symptoms
- Severe fatigue, weakness, pallor and other issues
Cause of Anemia
- Spleen destruction and intravascular hemolysis
- Sickle cells have a lifespan of 10-20 days, and normal cells have a lifespan of 90-120 days
Sickle Crisis
- Death of tissue
- Occurs in liver, joint, bones, heart, lungs, spleen, and kidneys
Splenic Infarction
- Autosplenectomy -> predisposes patient to infection, causing increased morbidity and mortality
- Excessive deO2 of RBC -> Crisis (dehydration, infection, violent exercise, altitude, cold, anesthesia)
Homozygote
- Can't produce HbA (0%) -> HbS (90%), remain HbF (5-10%)
- HbA2 is unimportant
- Africa can't HbF compensate -> sick
- Arabs can have HbF -> 40-50% - 60%, normal, don't sickle
Laboratory Diagnosis
- Hb is 5-9mg/dL
- Normocytic/slight hypochromic
- Look for sickle cells/target cells, nRBCs, Polyachromasia and stippled RBC
- Also look for HJB
Electrophoresis
- HbS (90-95%)
- HbF (5-10%)
- HbA2 (var)
Treatment
- Transfusion and iron chelation, pain management, Hydroxyurea, HbF
- Bone marrow/stem cell transplant
Heterozygote
- Autosomal recessive, short arm of chromosome 11
- HbA: 60-70%
- HbS: 30-40% -> no sickling, normal RBC
Sickling Test
- 1-2 drops of blood + Sodium metabisulfate (2%)
- Then coverslip -> leafy
Solubility
- HbS less soluble -> turbid + dithionite
Electrophoresis
- HbA (60-70%)
- HbS (30-40%)
- HbA2 & HbF normal
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