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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?
- Inversion on chromosome 2
- Point mutation in splice sites (correct)
- Deletion of the ß-globin gene
- Translocation of chromosome 11
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?
Lead inhibits heme synthesis.
Lead inhibits heme synthesis.
What treatment is used for lead poisoning?
What treatment is used for lead poisoning?
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.
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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