Thalassemia

Introduction

Thalassemia is an inherited blood disorder that causes body to have less hemoglobin than normal. Thalassemia patients are not able to make enough hemoglobin, which causes severe anemia. Hemoglobin is found in red blood cells and carries oxygen to all parts of the body. When there is not enough hemoglobin in the red blood cells, oxygen cannot get to all parts of the body. Organs then become starved for oxygen and are unable to function properly.In the normal adult, hemoglobin A, which is composed of two alpha and two beta globins (A2Β2), is the most prevalent, comprising about 98% of all hemoglobin. Two minor hemoglobin also occur: hemoglobin A2, composed of two alpha and two sigma globins (α2 δ2) comprises 2-3.5% of hemoglobin, while hemoglobin F, composed of two alpha and two gamma globins (α2 γ2) comprises less than 2% of hemoglobin. Hemoglobin F, or fetal hemoglobin, is produced by the fetus in utereo and until about 48 weeks after birth.The genes controlling globin production are on chromosome 16 (alpha globin genes: 'α'), and chromosome 11 (beta: 'β', gamma: 'γ', and delta: 'δ' genes).

Types of Thalassemia

Beta Thalassemia: if the beta globin chain synthesis is reduced. It is more common. It is divided into thalassemia minor and thalassemia major.

Alpha Thalassemia: if the alpha globin chain is reduced. It is further divided into thalassemia minor and thalassemia major.

Beta thalassemia major Clinical features (S/S)

• Growth retardation
• Intermittent infection
• Severe anemia
• Bone marrow hyperplasia
• Splenomegaly
• Hepatomegaly

Diagnosis: Beta thalassemia major

Severe microcytic hypochromic anemia

Peripheral film is bizzare showing severe microcytosis, hypochromia, poikilocytosis and basophilic stippling

Hemoglobin electrophoresis shows major portion of fetal hemoglobin (HbF) and marked reduction or absent adult hemoglobin (HbA) with variable amount of HbA2

X-ray of skull showing ‘hair on end’ appearance

Beta thalassemia minor

Microcytic hypochromic anemia

Hemoglobin electrophoresis usually shows a raised HbA2 (4-8%) and often a raised Hb F (1-5%)

Treatment of Beta Thalassemia major

• Blood transfusion regularly every 4-6 weeks to keep the hemoglobin above 10g/dl
• Folic acid 5mg/day
• Splenectomy- if hypersplenism cause a marked increase in transfusion requirement
• Inj. Desferoxamine as a 12h infusion (prevents iron overload due to repeat blood transfusion)

Diagnosis of alpha thalassemia: Thalassemia minor

• Mild microcytic hypochromic anemia
• Hemoglobin electrophoresis shows no increase in percentage of Hb A2 or Hb F, there is no Hb H

Hemoglobin H disease

• Microcytic hypochromic anemia of variable severity
• Hemoglobin electrophoresis shows presence of Hb H that comprises 10-40% of hemoglobin

Treatment of Alpha Thalassemia

• Alpha thalassemia trait patients require no treatment
• Patients with hemoglobin H disease should take folic acid 5mg/day and avoid oxidative drugs such as sulfonamides