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Questions and Answers
What is the main characteristic of hemoglobin disorders?
What is the main characteristic of hemoglobin disorders?
- Gene mutations affecting Hb production switching
- Qualitative defects resulting from single amino acid substitutions (correct)
- Reduced rate of synthesis of one or more globin chains
- Quantitative defects in globin chain synthesis
What is the effect of the mutation in sickle cell hemoglobinopathy?
What is the effect of the mutation in sickle cell hemoglobinopathy?
- Increases the stability of the Hb molecule
- Affects the stability of the Hb molecule during hypoxia (correct)
- Decreases the oxygen affinity of the Hb molecule
- Increases the synthesis of HbS chains
What is the result of homozygous occurrence of the sickle gene?
What is the result of homozygous occurrence of the sickle gene?
- Severe, chronic hemolytic anemia (correct)
- Mild anemia and hemolysis
- Benign clinical course with no anemia
- No effect on hemoglobin synthesis
What is the characteristic of thalassemias?
What is the characteristic of thalassemias?
What is the effect of the substitution of glutamic acid with valine in sickle cell hemoglobinopathy?
What is the effect of the substitution of glutamic acid with valine in sickle cell hemoglobinopathy?
What is the result of heterozygous occurrence of the sickle gene?
What is the result of heterozygous occurrence of the sickle gene?
What is the group of gene mutations that interfere with the switching of fetal to adult Hb production known as?
What is the group of gene mutations that interfere with the switching of fetal to adult Hb production known as?
What percentage of HbS is found in the red cells of individuals with sickle cell anemia?
What percentage of HbS is found in the red cells of individuals with sickle cell anemia?
What is the primary characteristic of thalassemia syndromes?
What is the primary characteristic of thalassemia syndromes?
Which chromosomes are involved in the production of hemoglobin?
Which chromosomes are involved in the production of hemoglobin?
What is the commonest type of β-thalassemia?
What is the commonest type of β-thalassemia?
What is the net result of the hemolytic component of the disease?
What is the net result of the hemolytic component of the disease?
What is the result of the free α chains forming α-globin tetramers?
What is the result of the free α chains forming α-globin tetramers?
At what age is the onset of the disease usually seen?
At what age is the onset of the disease usually seen?
What is a characteristic of α-thalassemia?
What is a characteristic of α-thalassemia?
What is the characteristic feature of blood smear in chronic hemolytic anemia?
What is the characteristic feature of blood smear in chronic hemolytic anemia?
What is the genotype of a person with β-thalassemia minor?
What is the genotype of a person with β-thalassemia minor?
What is the risk of thalassemia major when both parents have thalassemia trait?
What is the risk of thalassemia major when both parents have thalassemia trait?
What is a common manifestation of hemosiderosis?
What is a common manifestation of hemosiderosis?
What is the effect of the disease on erythropoiesis?
What is the effect of the disease on erythropoiesis?
What is the minimum volume of packed RBCs required per year?
What is the minimum volume of packed RBCs required per year?
What is the range of HbA2 in β-thalassemia trait?
What is the range of HbA2 in β-thalassemia trait?
What is a common feature of chronic hemolytic anemia?
What is a common feature of chronic hemolytic anemia?
What percentage of HbF is raised in chronic hemolytic anemia?
What percentage of HbF is raised in chronic hemolytic anemia?
Why should splenectomy be delayed until after 5-6 years of age?
Why should splenectomy be delayed until after 5-6 years of age?
What is the goal of blood transfusion in chronic hemolytic anemia?
What is the goal of blood transfusion in chronic hemolytic anemia?
What is a characteristic of red blood cells in β-thalassemia trait?
What is a characteristic of red blood cells in β-thalassemia trait?
What is the most effective treatment for chronic hemolytic anemia?
What is the most effective treatment for chronic hemolytic anemia?
What is the term for the loss of all marrow elements leading to anemia, leukopenia, and thrombocytopenia?
What is the term for the loss of all marrow elements leading to anemia, leukopenia, and thrombocytopenia?
What is the term for a marked decrease or absence of blood-forming elements in the bone marrow?
What is the term for a marked decrease or absence of blood-forming elements in the bone marrow?
What is the characteristic feature of Fanconi anemia?
What is the characteristic feature of Fanconi anemia?
What is the primary goal of general care in pancytopenia?
What is the primary goal of general care in pancytopenia?
What is a common complication of pancytopenia?
What is a common complication of pancytopenia?
What is the only curative therapy for pancytopenia?
What is the only curative therapy for pancytopenia?
What is a characteristic laboratory finding in pancytopenia?
What is a characteristic laboratory finding in pancytopenia?
What is a possible treatment for pancytopenia if bone marrow transplantation is not available?
What is a possible treatment for pancytopenia if bone marrow transplantation is not available?
What is a characteristic feature of acquired pancytopenia?
What is a characteristic feature of acquired pancytopenia?
What is a common cause of acquired pancytopenia?
What is a common cause of acquired pancytopenia?
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Study Notes
Hemoglobin Disorders
- Hemoglobin disorders are qualitative defects resulting from single amino acid substitution in the alpha or beta chains of adult hemoglobin.
- These defects affect the stability of the Hb molecule and alter its oxygen affinity.
Structural Hemoglobin Variants
- These are qualitative defects that result from single amino acid substitution in the alpha or beta chains of adult hemoglobin.
- Examples include sickle cell hemoglobinopathy.
Sickle Cell Hemoglobinopathy
- Characterized by a structural defect of β chains of hemoglobin where glutamic acid in position number 6 is replaced by valine (α2-β2 6 val).
- This minor defect affects the stability of the Hb molecule during hypoxia, distorting the red cell membrane and forming sickled cells.
Sickle Cell Anemia
- Homozygous occurrence of the sickle gene with two abnormal genes results in severe, chronic hemolytic anemia.
- Heterozygous occurrence of the sickle gene (one abnormal gene) has red cells containing 35-45% Hb S, usually with a benign clinical course with mild anemia and hemolysis.
Thalassemias
- A heterogeneous group of inherited disorders characterized by hypochromic anemia caused by deficient synthesis of one or more of the polypeptide chains of human Hb.
- Two hemoglobin gene clusters are involved in the production of Hb and are located on chromosomes 11 and 16.
β-Thalassemia
- Decrease in the formation of β chains (HbA) with the formation of γ chains (HbF) and δ chains (HbA2) to compensate for the deficiency of adult Hb.
- Four grades of β thalassemia:
- Silent carrier (asymptomatic)
- β-thalassemia trait (mild anemia)
- β-thalassemia intermedia (moderate anemia)
- β-thalassemia major (hydrops fetalis)
α-Thalassemia
- Disorders caused by reduced synthesis or absent synthesis of α globin chains.
- Four clinical types:
- Hemoglobin H disease
- β-thalassemia minor
- α-thalassemia trait
- α-thalassemia major
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