Beta thalassemia

Beta thal – variable levels of beta chain synthesis; 2 genes on chromosome 11

• Presentation depends on type of mutation

  • β – Normal production

  • β+ – Decreased β chain production

  • β0 – No β chain production

• Damage is from precipitation of α chains

• trait – heterozygote; asymptomatic with palpable spleen; mild anemia with increase in RBC
• disease – homozygote; severe anemia requiring transfusions; hepatosplenomegaly with extramedullary hematopoesis, jaundice

β/β+ and β/β0

• “Silent carrier or beta thal minor”

• Mild anemia (2-3 g/dL below normal)

• Low MCV

• Often misdiagnosed as Fe deficiency

• Mentzer index (MCV/RBC #) <13

• Increased Hgb A2 (α2δ2) on Hgb

• electrophoresis

β+/β+

• “Thalassemia intermedia”

• Moderate anemia

• (Hgb 6-8 mg/dL)

• Moderate elevation of Hgb F (60-80%)

β Thalassemia Major (β0/β0) aka Cooley anemia

• Present in 2nd 6mos of life

• Severe hemolytic anemia

• Extramedullary hematopoesis

• HSM

• Bone marrow, face/skull bones expand

• Green/brown skin color

  • Pallor

  • Jaundice

• Hemosiderosis

  • Pancreas (DM)

  • Heart (arrhythmia, CHF)

• Laboratory findings

  • Severe hypochromic, microcytic anemia

  • Poikilocytosis, target cells

  • Hgb <5

  • Unconjugated bilirubin elevation

  • TIBC low (all sites bound)

  • Fe level high

  • Fetal hemoglobin level: >90%

• Therapy

  • Regular transfusions (q 4-5 weeks)

  • Deferoxamine (Fe chelator)

  • Splenectomy

  • Indicated for hypersplenism or progressive

  • enlargement

  • BMT

• Picture: frontal bossing, maxillary hyperplasia, (2) Hair on end skull