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Questions and Answers
Sickle cell disease affects red blood cells by causing them to have a circular ______ shape instead of the normal biconcave shape.
Sickle cell disease affects red blood cells by causing them to have a circular ______ shape instead of the normal biconcave shape.
C
Individuals with sickle cell disease have an increased risk of ______ due to blockages in the blood vessels.
Individuals with sickle cell disease have an increased risk of ______ due to blockages in the blood vessels.
infection
One of the causes of sickle cell disease is a mutation in the ______ gene.
One of the causes of sickle cell disease is a mutation in the ______ gene.
HBB
Sickle cell trait is represented by the genotype ______.
Sickle cell trait is represented by the genotype ______.
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One treatment option for sickle cell disease is ______ transfusions to replace defective red blood cells.
One treatment option for sickle cell disease is ______ transfusions to replace defective red blood cells.
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Individuals with sickle cell disease can experience acute ______ due to tissue damage caused by blockages.
Individuals with sickle cell disease can experience acute ______ due to tissue damage caused by blockages.
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Hydration helps to prevent red blood cells from ______ more easily.
Hydration helps to prevent red blood cells from ______ more easily.
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The mutation in sickle cell disease involves a change from ______ to GTG in the HBB gene.
The mutation in sickle cell disease involves a change from ______ to GTG in the HBB gene.
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Sickle cell disease causes red blood cells to become less ______, making it difficult for them to pass through blood vessels.
Sickle cell disease causes red blood cells to become less ______, making it difficult for them to pass through blood vessels.
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Individuals with sickle cell disease often experience ______ as a result of reduced oxygen distribution to organs.
Individuals with sickle cell disease often experience ______ as a result of reduced oxygen distribution to organs.
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Blockages caused by deformed red blood cells can lead to ______ and necrosis of organs.
Blockages caused by deformed red blood cells can lead to ______ and necrosis of organs.
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Heterozygous genotype has a higher relative ______ than either homozygous dominant or homozygous recessive genotype.
Heterozygous genotype has a higher relative ______ than either homozygous dominant or homozygous recessive genotype.
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One of the suggested treatments for sickle cell disease is to keep patients well ______ to reduce RBC polymerization.
One of the suggested treatments for sickle cell disease is to keep patients well ______ to reduce RBC polymerization.
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In sickle cell trait, individuals possess one mutated allele (HbS) and one normal allele (HbA), making them ______ carriers.
In sickle cell trait, individuals possess one mutated allele (HbS) and one normal allele (HbA), making them ______ carriers.
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Gene therapy for sickle cell disease involves cutting DNA to turn off ______, allowing for the production of fetal hemoglobin.
Gene therapy for sickle cell disease involves cutting DNA to turn off ______, allowing for the production of fetal hemoglobin.
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Sickle cell disease is one of the most common ______ disorders.
Sickle cell disease is one of the most common ______ disorders.
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What is a potential complication of sickle cell disease that affects the spleen?
What is a potential complication of sickle cell disease that affects the spleen?
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What is the average life expectancy for individuals with sickle cell disease in developed countries?
What is the average life expectancy for individuals with sickle cell disease in developed countries?
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Which of the following is a common symptom of sickle cell disease?
Which of the following is a common symptom of sickle cell disease?
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Which population is typically associated with a higher prevalence of sickle cell disease?
Which population is typically associated with a higher prevalence of sickle cell disease?
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What is a primary reason individuals with sickle cell disease experience delayed growth?
What is a primary reason individuals with sickle cell disease experience delayed growth?
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What percentage of children born to parents with one normal hemoglobin allele and one sickle cell trait allele may inherit sickle cell disease?
What percentage of children born to parents with one normal hemoglobin allele and one sickle cell trait allele may inherit sickle cell disease?
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Which condition is NOT a symptom of malaria?
Which condition is NOT a symptom of malaria?
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How does the HbS allele relate to malaria resistance in sickle cell trait carriers?
How does the HbS allele relate to malaria resistance in sickle cell trait carriers?
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What is the role of the CRISPR–Cas9 gene-editing tool in the treatment of sickle cell disease?
What is the role of the CRISPR–Cas9 gene-editing tool in the treatment of sickle cell disease?
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Which of the following is a characteristic of individuals with sickle cell trait?
Which of the following is a characteristic of individuals with sickle cell trait?
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What is one risk associated with individuals who have sickle cell trait?
What is one risk associated with individuals who have sickle cell trait?
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What is the primary method used to screen for sickle cell disease in newborns?
What is the primary method used to screen for sickle cell disease in newborns?
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Which type of sickle cell disease involves one sickle cell gene and one abnormal hemoglobin C gene?
Which type of sickle cell disease involves one sickle cell gene and one abnormal hemoglobin C gene?
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What is the typical severity of HbAS, known as sickle cell trait?
What is the typical severity of HbAS, known as sickle cell trait?
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In the mutant HBB gene (HbS), which amino acid is Valine substituted for at position 6?
In the mutant HBB gene (HbS), which amino acid is Valine substituted for at position 6?
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What is the hemoglobin type present in patients with Sickle Cell Anemia (HbSS)?
What is the hemoglobin type present in patients with Sickle Cell Anemia (HbSS)?
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Which hemoglobin variant is associated with a mutation resulting in the glumatic acid to lysine substitution?
Which hemoglobin variant is associated with a mutation resulting in the glumatic acid to lysine substitution?
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What defines HbS β+ thalassemia?
What defines HbS β+ thalassemia?
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Which of the following hemoglobin types is typically the most severe?
Which of the following hemoglobin types is typically the most severe?
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What is one of the potential long-term effects of sickle cell disease on growth?
What is one of the potential long-term effects of sickle cell disease on growth?
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Which of the following symptoms is NOT commonly associated with sickle cell disease?
Which of the following symptoms is NOT commonly associated with sickle cell disease?
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What is the average life expectancy for individuals with sickle cell disease in developing nations?
What is the average life expectancy for individuals with sickle cell disease in developing nations?
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Which type of sickle cell disease results from the combination of one sickle cell gene and one abnormal hemoglobin C gene?
Which type of sickle cell disease results from the combination of one sickle cell gene and one abnormal hemoglobin C gene?
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What complication associated with sickle cell disease may lead to significant organ damage due to reduced blood flow?
What complication associated with sickle cell disease may lead to significant organ damage due to reduced blood flow?
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What genetic inheritance pattern is associated with Sickle Cell Disease?
What genetic inheritance pattern is associated with Sickle Cell Disease?
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How does the HbS allele impact individuals with Sickle Cell Trait (HbAS) in terms of malaria resistance?
How does the HbS allele impact individuals with Sickle Cell Trait (HbAS) in terms of malaria resistance?
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What is a notable consequence of having Sickle Cell Trait (HbAS) under certain conditions?
What is a notable consequence of having Sickle Cell Trait (HbAS) under certain conditions?
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What screening test is commonly used for detecting Sickle Cell Disease in newborns?
What screening test is commonly used for detecting Sickle Cell Disease in newborns?
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Which gene-editing tool has been approved for use in treating Sickle Cell Disease?
Which gene-editing tool has been approved for use in treating Sickle Cell Disease?
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Which of the following statements is true regarding individuals with HbSS genotype?
Which of the following statements is true regarding individuals with HbSS genotype?
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What potential risk is associated with being a carrier of the HbS allele regarding offspring?
What potential risk is associated with being a carrier of the HbS allele regarding offspring?
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What is the primary genetic inheritance pattern of sickle cell anemia (HbSS)?
What is the primary genetic inheritance pattern of sickle cell anemia (HbSS)?
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In the case of HbSC, what type of gene is present alongside the sickle cell gene?
In the case of HbSC, what type of gene is present alongside the sickle cell gene?
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Which hemoglobin type represents the mildest form associated with sickle cell disease?
Which hemoglobin type represents the mildest form associated with sickle cell disease?
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What amino acid substitution occurs in the mutant HBB (HbS) gene at position 6?
What amino acid substitution occurs in the mutant HBB (HbS) gene at position 6?
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What does HbF represent in the context of hemoglobin variants?
What does HbF represent in the context of hemoglobin variants?
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Which term describes the group of disorders with reduced levels of hemoglobin?
Which term describes the group of disorders with reduced levels of hemoglobin?
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What is the consequence of having one sickle cell gene and one β0 thalassemia gene?
What is the consequence of having one sickle cell gene and one β0 thalassemia gene?
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Which of the following is NOT a symptom commonly associated with sickle cell disease?
Which of the following is NOT a symptom commonly associated with sickle cell disease?
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What is a significant complication of sickle cell disease that can lead to organ damage?
What is a significant complication of sickle cell disease that can lead to organ damage?
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Which population typically has increased prevalence of sickle cell disease?
Which population typically has increased prevalence of sickle cell disease?
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Which of the following conditions is a potential long-term effect of sickle cell disease on the body?
Which of the following conditions is a potential long-term effect of sickle cell disease on the body?
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Which individual is most likely to have sickle cell disease?
Which individual is most likely to have sickle cell disease?
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What is a characteristic of individuals with sickle cell trait (HbAS)?
What is a characteristic of individuals with sickle cell trait (HbAS)?
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What is one potential risk for parents with one normal hemoglobin allele and one sickle cell trait allele?
What is one potential risk for parents with one normal hemoglobin allele and one sickle cell trait allele?
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What is the primary method of screening for sickle cell disease in newborns?
What is the primary method of screening for sickle cell disease in newborns?
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Which gene-editing technology has been approved for treating sickle cell disease?
Which gene-editing technology has been approved for treating sickle cell disease?
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What is a significant complication associated with sickle cell trait under extreme conditions?
What is a significant complication associated with sickle cell trait under extreme conditions?
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How does the HbS allele confer some resistance against malaria?
How does the HbS allele confer some resistance against malaria?
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Which of the following conditions is NOT a symptom of malaria?
Which of the following conditions is NOT a symptom of malaria?
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Which hemoglobin variant is characterized by the presence of two alpha and two gamma chains?
Which hemoglobin variant is characterized by the presence of two alpha and two gamma chains?
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Sickle Cell Anemia, or HbSS, is inherited through which genetic pattern?
Sickle Cell Anemia, or HbSS, is inherited through which genetic pattern?
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Which amino acid is replaced by Valine in the mutant HBB gene for HbS?
Which amino acid is replaced by Valine in the mutant HBB gene for HbS?
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What is the typical severity of the HbSC genotype?
What is the typical severity of the HbSC genotype?
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What is the primary characteristic of the HbS β0 - thalassemia type?
What is the primary characteristic of the HbS β0 - thalassemia type?
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In the context of sickle cell genetics, what does HbCD represent?
In the context of sickle cell genetics, what does HbCD represent?
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What is one of the genetic factors contributing to Sickle Cell Trait (HbAS)?
What is one of the genetic factors contributing to Sickle Cell Trait (HbAS)?
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What primary protein affects the oxygen-carrying capacity of sickle cells?
What primary protein affects the oxygen-carrying capacity of sickle cells?
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Study Notes
Sickle Cell Disease
- Definition: A genetic disorder caused by a mutation in the HBB gene, resulting in abnormal haemoglobin.
- Abnormal Red Blood Cells (RBCs): Sickle cell RBCs have a crescent (C) shape instead of the normal biconcave shape, making them less flexible and prone to blockages.
- Mechanism of Defect: The mutation (GAG to GTG) causes valine to replace glutamic acid in the beta-globin chain. This hydrophobic change alters the haemoglobin structure, leading to abnormal RBC shape.
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Consequences:
- Vasooclusive Crisis: Blockages due to sickle-shaped RBCs lead to hypoxia (low oxygen) and organ damage. Symptoms include acute pain, damage to bones, kidneys and potential death.
- Reduced Oxygen Transport: The abnormal shape of the RBCs causes them to die more quickly. Limited oxygen transport throughout the body leads to various symptoms.
- Anemia: A lack of adequate, healthy red blood cells due to early destruction and blockage leading to poor oxygen delivery to organs causing fatigue, headaches, irregular heartbeats, and shortness of breath.
- Genetic Basis: The mutated HBB gene produces abnormal haemoglobin (HbS), instead of the normal haemoglobin (HbA). Another mutation (GAG to AAG) results in HbC.
- Sickle Cell Trait (HbAS): Individuals with one normal allele (HbA) and one mutated allele (HbS) usually do not have symptoms. However, stressors like intense exercise, high altitudes or scuba diving can trigger a sickling crisis potentially leading to fatal lack of oxygen.
- Increased Infection Risk: Patients are vulnerable to infections due to the compromised immune system.
Sickle Cell Disease - Diagnosis and Treatment
- Diagnosis: Blood tests are used to identify the genetic mutation that causes sickle cell disease. All newborns in the UK are screened.
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Treatment:
- Hydration: Maintaining adequate hydration helps prevent sickling.
- Vaccination: Regular vaccinations are essential to prevent infections.
- Drugs: Drugs which increase fetal hemoglobin levels can help by bypassing the need for beta hemoglobin.
- Blood Transfusions: Replacement of diseased RBCs with healthy ones.
- Bone Marrow Transplantation: Healthy RBC production using stem cells can replace damaged stem cells.
- Gene Therapy: Techniques that aim to correct the genetic defect by turning off BCL11A, an important gene, thereby encouraging production of fetal haemoglobin.
Sickle Cell Disease - Relevance to Malaria
- Malaria Resistance: Individuals with sickle cell trait (HbAS) show some resistance to malaria. The abnormal haemoglobin may offer protection against malaria either by enhanced immunity, increasing clearance of infected red blood cells, or by reducing parasite growth.
- Malaria Risk for Sickle-Cell Disease: Individuals with sickle cell disease are more susceptible to fatal complications from malaria.
- Heterozygote Advantage: The sickle cell trait (HbAS) provides a survival advantage in regions with high malaria prevalence, as demonstrated by the relative fitness of the heterozygote genotype.
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Description
This quiz explores the genetic disorder known as sickle cell disease, focusing on its definition, abnormal red blood cell characteristics, and mechanisms of defect. Learn about the consequences such as vaso-occlusive crises, reduced oxygen transport, and anemia. Test your knowledge on this critical health topic.
