In alpha-thalassemia, one genetic mutation typically results in which condition?

• A. Patient considered a carrier
• B. No symptoms or signs of the disease
• C. Alpha-thalassemia minor
• D. Alpha-thalassemia major

Answer: (B)

In alpha-thalassemia, how many alpha-globin genes are affected determines the clinical picture. When only one alpha-globin gene is deleted, the body usually still makes enough alpha-globin to prevent anemia, so there are no symptoms or signs of the disease. This is why this state is described as a silent carrier. Lab studies might show normal results, though a mild reduction in red cell size (microcytosis) can sometimes be seen without causing symptoms. If more genes are affected, the condition becomes progressively more severe: two deletions lead to alpha-thalassemia trait with mild anemia, three deletions cause HbH disease, and all four deletions result in hydrops fetalis.