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Questions and Answers
What is the clinical outcome of Beta-thalassemia Major?
What is the clinical outcome of Beta-thalassemia Major?
Severe microcytic anemia with target cells and increased anisopoikilocytosis requiring blood transfusions.
What mutation results in beta-thalassemia?
What mutation results in beta-thalassemia?
What symptoms are associated with lead poisoning?
What symptoms are associated with lead poisoning?
Lead lines on gingivae, encephalopathy, abdominal colic, and drop-wrist.
Which of the following factors can lead to sideroblastic anemia?
Which of the following factors can lead to sideroblastic anemia?
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Lead inhibits heme synthesis.
Lead inhibits heme synthesis.
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What treatment is used for lead poisoning?
What treatment is used for lead poisoning?
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The presence of ______ can be observed in the bone marrow of patients with sideroblastic anemia.
The presence of ______ can be observed in the bone marrow of patients with sideroblastic anemia.
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What are the lab findings associated with sideroblastic anemia?
What are the lab findings associated with sideroblastic anemia?
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Study Notes
Beta-thalassemia
- Caused by point mutations on chromosome 11 affecting ß-globin synthesis.
- Commonly found in individuals of Mediterranean descent.
- Beta-thalassemia Minor: Mutation of 1 gene leads to mild microcytic anemia and increased HbA₂.
- Beta-Thalassemia Intermedia: Mutation of 2 genes (ß+/B+ or ß+/ߺ) results in variable anemia severity, from mild to transfusion-dependent.
- Beta-thalassemia Major: Mutation of 2 genes leads to severe microcytic anemia, requiring blood transfusions. Symptoms include target cells, anisopoikilocytosis, secondary hemochromatosis, marrow expansion ("crew cut" skull x-ray), splenomegaly, hepatomegaly, risk of parvovirus B19-induced aplastic crisis, increased HbF and HbA₂.
- Sickle Cell Beta-Thalassemia: Occurs with 1 gene mutated (ß+/HbS or Bº/HbS), leading to mild to moderate sickle cell disease based on the presence or absence of ß-globin synthesis.
Lead Poisoning
- Lead inhibits ferrochelatase and ALA dehydratase, reducing heme synthesis and increasing RBC protoporphyrin.
- Inhibits rRNA degradation, causing RBCs to retain aggregates of rRNA, observed as basophilic stippling.
- Symptoms include:
- Burton lines on gingivae and long bone metaphyses on x-ray.
- Encephalopathy.
- Abdominal colic and sideroblastic anemia.
- Neurological symptoms such as drop-wrist and foot drop.
- Treatment involves chelation therapy using succimer, EDTA, or dimercaprol.
- Increased exposure risk in pre-1978 homes with chipped paint and occupational settings.
Sideroblastic Anemia
- Causes can be genetic (X-linked ALA synthase defect), acquired (myelodysplastic syndromes), or reversible (alcohol, lead poisoning, vitamin B6 deficiency, copper deficiency, certain drugs like isoniazid and linezolid).
- Lab findings include:
- Increased iron levels.
- Normal or increased Total Iron Binding Capacity (TIBC).
- Increased ferritin levels.
- Presence of ringed sideroblasts in bone marrow with iron-laden mitochondria.
- Peripheral blood smear may show basophilic stippling of RBCs.
- Some acquired variants might present as normocytic or macrocytic anemias.
- Treatment includes pyridoxine (Vitamin B6), which acts as a cofactor for ALA synthase.
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Description
This quiz explores the genetic causes and clinical implications of Beta-thalassemia, a type of microcytic, hypochromic anemia. It examines the mutations affecting ß-globin synthesis and the prevalence of this disorder among various populations, particularly those of Mediterranean descent.
