Thalassemia

Background

• A group of hereditary disorders resulting in microcytic, hypochromic, hemolytic anemia
• Most common in Mediterranean, Middle Eastern, African and Southeast Asian population

Clinical Features

• Categorized depending on globin chain affected or the abnormal Hb produced
  • β-globin gene mutations cause β-thalassemia; ɑ-globin mutations cause ɑ-thalassema

ɑ-Thalassemia Carrier and Trait

• no clinical symptoms or physical findings
• microcytic RBCs and normal Hb level

Hemoglobin H Disease (HbH disease)

• one ɑ-globin chain gene is still functional
• typically presents in neonatal period with severe hypochromic anemia
• hypochromic, microcytic anemia with jaundice and hepatosplenomegaly
• may not require regular transfusions
• tranfusions may be necessary in setting of increased oxidative stress or infection which may precipitate hemolysis

β-Thalassemia Minor (β-Thalassemia Trait)

• heterozygous for β-globin mutation
• mild microcytic anemia
• splenomegaly uncommon
• microcytosis, hypochromia, basophilic stippling on blood smear
• no clinical symptoms

β-Thalassemia Major (Cooley Anemia)

• both β-globin genes defective; β-globin chain production severely impaired
• typically presents >6mos of life (HbF production replaced with β-globin to form HbA)
• hepatosplenomegaly, jaundice, expansion of erythroid marrow causing bone changes and osteoporosis, susceptible to infection
• severe anemia requiring regular and lifelong blood transfusions
  • iron overload secondary to frequent transfusions is etiology of most of morbidity and mortality
• low MCV with microcytic and hypochromic RBC

Sickle Cell-β-Thalassemia Disease

ɑ β