Ultrasound Obstet Gynecol

Apuntes

•β-thalassemia β-thalassemia is a hereditary microcytic anemia caused by mutations in the β-globin gene (HBB) that lead to reduced (β⁺) or absent (β⁰) synthesis of β-globin chains of hemoglobin. A nonsense mutation (C) introduces a premature stop codon, truncating translation and producing a nonfunctional or incomplete β-globin protein. In β⁰-thalassemia, this results in a complete absence of β-globin production, causing severe anemia, ineffective erythropoiesis, and compensatory bone marrow expansion. Clinically, patients often present with chronic fatigue, pallor, and exertional dyspnea, along with microcytic, hypochromic anemia on peripheral smear. Over time, severe cases may develop hepatosplenomegaly, iron overload, and characteristic skull X-ray findings due to marrow hyperplasia. Nonsense mutations differ from missense mutations (which change one amino acid) and splice site mutations (which affect mRNA processing), making this the most likely molecular defect in β⁰-thalassemia. This patient’s presentation—chronic fatigue, pallor, microcytic hypochromic anemia, and a confirmed point mutation in the beta-globin gene—is characteristic of a missense mutation causing sickle cel...