G6PD Deficiency Overview
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Questions and Answers

What is the primary cause of acute haemolytic anaemia described in the text?

  • Gradual decrease in red blood cell production
  • Iron deficiency
  • Slowly developing extravascular hemolysis
  • Rapidly developing intravascular hemolysis with haemoglobinuria (correct)

    • Between crises, the blood count is always abnormal in patients with G6PD deficiency.

    False (B)

    What might a blood film show during a haemolytic crisis in a patient with G6PD deficiency?

    Contracted and fragmented cells, bite cells / blister cells

    _______ bodies are oxidized, denatured haemoglobin that may be seen in reticulocyte preparation.

    <p>Heinz</p> Signup and view all the answers

    Match the following diagnostic findings with their descriptions:

    <p>Bite Cells = Red blood cells with portions removed, often related to spleen activity. Heinz Bodies = Oxidized, denatured haemoglobin. Haemoglobinuria = Presence of free haemoglobin in the urine. Blister Cells = Red blood cells with one or more vesicles.</p> Signup and view all the answers

    Why might a red cell enzyme assay give a false normal level during an acute haemolytic phase?

    <p>Young red cells have higher enzyme levels. (D)</p> Signup and view all the answers

    Prussian blue-positive deposits of haemosiderin can be found in urine samples during acute episode of intravascular haemolysis.

    <p>True (A)</p> Signup and view all the answers

    What causes the red cells to become rigid in Pyruvate kinase deficiency?

    <p>Reduced adenosine triphosphate (ATP) formation</p> Signup and view all the answers

    Which group of individuals is primarily affected by G6PD deficiency?

    <p>Males only (A), Females who are heterozygous (C)</p> Signup and view all the answers

    G6PD deficiency renders red blood cells more susceptible to oxidant stress.

    <p>True (A)</p> Signup and view all the answers

    What is the primary function of G6PD in the body?

    <p>To reduce NADP to NADPH</p> Signup and view all the answers

    G6PD deficiency is the most prevalent enzyme deficiency affecting over _______ million people worldwide.

    <p>400</p> Signup and view all the answers

    Match the following causes of oxidant stress with their corresponding categories:

    <p>Fava beans = Food Infections = Illness Chloroquine = Drug Chloramphenicol = Drug</p> Signup and view all the answers

    What is the most common type of G6PD variant in black Africans?

    <p>Type A (B)</p> Signup and view all the answers

    Reduced glutathione (GSH) is essential for RBCs to eliminate free radicals.

    <p>True (A)</p> Signup and view all the answers

    Which enzyme is solely responsible for producing NADPH?

    <p>G6PD</p> Signup and view all the answers

    Flashcards

    G6PD Deficiency

    Most common enzyme deficiency affecting over 400 million people.

    Inheritance of G6PD Deficiency

    Sex-linked inheritance; males are affected, females are carriers.

    Role of NADPH

    NADPH, produced by G6PD, detoxifies free radicals and helps in RBC maintenance.

    Function of Reduced Glutathione (GSH)

    Critical in protecting RBCs from oxidative stress.

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    Oxidant Stress Triggers

    Fava beans, infections, and certain drugs can cause oxidative crisis in G6PD deficient individuals.

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    Epidemiology of G6PD

    Multiple genetic variants exist, the most common being Type A, which is mild.

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    Acute Hemolytic Anemia

    Clinical feature of G6PD deficiency during oxidative stress events.

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    Hexose Monophosphate Shunt

    Pathway vital for producing NADPH, which supports G6PD function.

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    Bite cells

    Red blood cells with parts missing, often due to spleen action on Heinz bodies.

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    Heinz bodies

    Oxidized, denatured hemoglobin visible in red cells, particularly if the spleen is absent.

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    Enzyme deficiency screening

    Tests used to detect specific enzyme levels in red cells for diagnosis.

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    Reticulocyte response

    Increase in reticulocytes (young red cells) during a haemolytic crisis, affecting enzyme assay results.

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    Treatment of G6PD deficiency

    Involves stopping the wrong medication, treating infections, and possibly transfusions.

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    Urine samples in haemolysis

    Tests may show haemosiderin deposits in urine during acute haemolysis.

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    Pyruvate kinase deficiency

    A genetic disorder leading to rigid red cells due to low ATP formation and inherited recessively.

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    Study Notes

    Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency

    • G6PD deficiency is the most prevalent enzyme deficiency globally, affecting over 400 million people.
    • Inheritance is X-linked, primarily impacting males.
    • Female heterozygotes have a resistance benefit against Falciparum malaria.
    • Predominant regions affected include West Africa, the Mediterranean, the Middle East, and South-East Asia.

    Functions of G6PD

    • G6PD converts nicotinamide adenine dinucleotide phosphate (NADP) to NADPH.
    • NADPH is crucial for:
      • Producing reduced glutathione (GSH).
      • Converting oxidized hemoglobin (methemoglobin) to reduced hemoglobin.

    Reduced Glutathione (GSH)

    • RBCs need GSH to neutralize free radicals (H₂O₂).
    • G6PD deficiency makes red blood cells vulnerable to oxidative stress.

    Hexose Monophosphate Shunt Pathway

    • Oxidative stress leads to red blood cell membrane damage, forming Heinz bodies.
    • The pathway plays a crucial role in maintaining red blood cell function by providing NADPH to reduce oxidative stress.

    Cause of Oxidant Stress in G6PD Deficiency

    • Fava beans (and potentially other vegetables) can trigger crises.
    • Infections and conditions like diabetic ketoacidosis.
    • Medications, such as antimalarials (e.g., chloroquine), sulphonamides, antibacterial agents (e.g., chloramphenicol), and even some analgesics (e.g., aspirin) at high doses.

    Epidemiology of G6PD Deficiency

    • G6PD exists in various genetic forms; type A is commonly observed in African populations and is typically milder.
    • Type B, is prevalent in Western populations and is more severe.
    • Over 400 different G6PD variants exist, originating from point mutations or deletions. Many show reduced activity compared to normal.

    Clinical Features of G6PD Deficiency

    • Acute hemolytic anaemia is triggered by oxidative stress.
    • Rapid intravascular hemolysis causes hemoglobinuria.
    • Anemia's severity is potentially self-limiting, as new, healthy red blood cells are produced with nearly normal enzyme levels.
    • Neonatal jaundice is possible.

    Diagnosis of G6PD Deficiency

    • Between hemolytic episodes, blood counts are typically normal.
    • Enzyme deficiency is diagnosed via screening tests or direct assays on red blood cells.
    • During a crisis, blood films may show contracted and fragmented cells (bite/blister cells) and Heinz bodies.
    • Heinz bodies (oxidized hemoglobin) can be detected in reticulocyte preparations—especially if the spleen is absent.
    • Evidence of intravascular hemolysis is also observed.
    • False-normal enzyme levels can occur in young red blood cells during hemolysis, necessitating follow-up testing after the acute phase.
    • Urine samples in hemolytic episodes frequently show Prussian blue-positive deposits of hemosiderin.

    Treatment of G6PD Deficiency

    • Removing the causative drug and treating any concurrent infection is crucial.
    • Blood transfusions are necessary for severe anemia.
    • Neonatal jaundice in G6PD-deficient babies may warrant phototherapy and, in severe cases, exchange transfusions. Jaundice is not usually from hemolysis, but rather from the G6PD deficiency affecting the neonatal liver's function.

    Pyruvate Kinase Deficiency

    • An autosomal recessive condition affecting red blood cells. It is homozygous or doubly heterozygous.

    • Red blood cells become rigid due to decreased adenosine triphosphate (ATP) production.

    • Anemia severity varies widely (hemoglobin levels of 4-10 g/dL) causing relatively mild symptoms.

    • An intracellular shift regarding the oxygen dissociation curve is caused by an elevated level of 2,3-DPG. This causes frequent jaundice and gallstones.

    • Frontal bossing, poikilocytosis, and distorted red blood cells, especially post-splenectomy, may be present.

    • Direct enzyme assays are vital for diagnosis.

    • Splenectomy can be helpful for improving anemia but is not a cure, especially for those requiring frequent transfusions.

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    Related Documents

    Glucose-6-Phosphate Dehydrogenase Deficiency PDF

    Description

    This quiz explores the essential aspects of Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency, including its global prevalence, inheritance patterns, and the role of G6PD in cellular functions. Additionally, it covers the significance of reduced glutathione and the impact of G6PD deficiency on red blood cells under oxidative stress.

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