Thalassemia Overview

Thalassemia is a group of inherited disorders characterized by a deficiency in hemoglobin production, leading to anemia.

Key Symptoms

• Weakness
• Paleness
• Shortness of breath
• Headaches
• Dizziness
• Fainting

Hemoglobin Structure

• Adult Hemoglobin (Hemoglobin A): Composed of 2 alpha and 2 beta subunits.
• Fetal Hemoglobin: Composed of 2 alpha and 2 gamma chains.

Gene Encoding

• Alpha Subunit: Encoded by two HbA genes on chromosome 16 (4 copies total: 2 from each parent).
• Beta Subunit: Encoded by the Hbb gene on chromosome 11 (2 copies total: 1 from each parent).

Types of Thalassemia

1. Alpha Thalassemia

   • Silent Carrier: 1 mutated copy, typically asymptomatic.
   • Alpha-Thalassemia Trait/Minor: 2 mutated copies; microcytic anemia with mild symptoms.
   • Hemoglobin H Disease: 3 mutated copies; moderate to severe anemia due to abnormal hemoglobin.
   • Lethal Condition: All 4 copies mutated; usually fatal in utero.

2. Beta Thalassemia

   • Beta Plus Mutations: Reduced production of beta-globin.
   • Beta Zero Mutations: No beta-globin production.
   • Severity Classifications:
     • Minor or Trait
     • Intermediate
     • Major (severe anemia)

Clinical Manifestations of Beta Thalassemia Major

• Severe anemia leading to bone marrow hyperactivity, causing:
  • Enlarged bone marrow and cranial bones (chipmunk face).
  • Growth impairment and prone to long bone fractures.
• Increased dietary iron absorption causing iron overload:
  • Affects heart, liver, and endocrine functions.
• Enlarged spleen and elevated bilirubin levels leading to jaundice.

Diagnosis

• Blood Tests:
  • Low hemoglobin levels
  • High red blood cell distribution width
  • Microcytic, hypochromic red blood cells
  • High red cell count, serum iron, and ferritin levels.
• Hemoglobin Electrophoresis: To detect abnormal hemoglobin forms.

Treatment Options

• Thalassemia Trait: Typically does not require treatment.
• Moderate to Severe Thalassemias:
  • Blood transfusions combined with iron chelation therapy to prevent overload.
  • Splenectomy and certain medications to reduce transfusion needs.
• Definitive Cure: Blood or bone marrow transplantation to replace mutated stem cells.

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