Thalassemia – Definition, Types, Diagnosis, Treatment

Thalassemia definitions

  • Thalassemia is an inherited blood disorder in which the body produced an abnormal form of hemoglobin which results in excessive destruction of RBCs & further leads to anemia.
  • Thalassemia is a heterogeneous group of disorder characterized by a genetically determined and reduction in the rate of synthesis of normal globin chain

Types of globin chains

  • Hb A; HbA has two Alpha globin chains and two Beta globin chains
  • Hb A1; Hb A1 has two Alpha globin chains and two delta globin chains
  • HbF (In fetal); Hb F has two alpha and two gamma chains
  • HbF (In fetal); Hb F has two alpha and two gamma chains

In case of Thalassemia, We are having reduce production of one or more of these normal globin chains.

Basically, These are two types of Thalassemia

  • Alpha Thalassemia – reduced production of the normal Alpha globin chain
  • Beta Thalassemia – Reduced production of the normal Beta globin chain

Beta Thalassemia

Beta Thalassemia means having decrease production of normal Beta globin chains.

Genetic basis of Beta Thalassemia

  • Encoding genes on chromosome 11 (Short arm)
  • Beta Thalassemia occurs due to mutation of the gene
There are two types of mutations that can occur in that gene
  • β+ mutation: β+ mutation means we cannot produce a sufficient amount of Beta globin chain. However, there is little bit of Beta globin chain production
  • βo mutation : cannot produce any of Beta chains

Normal genotype is ββ, In here some may have ββ+,β+β+,βoβo.

Beta Thalassemia is subdivided into,

  • Beta Thalassemia minor: ββ+ , this kind of patient may have mild anemia and also asymptomatic.
  • Beta Thalassemia major: βoβ+/β+β+, This also known as Cooley’s anemia. In here, we are not producing any Beta chains. So we have a decreased amount of HbA. In other hemoglobins (HbA, HbF)They don’t need Beta. So these Hb may be increased. As a result, we cannot find Beta chains to make globin chains.so Alpha 2 bind Alpha 2 themself and form Alpha4. Alpha 4 containing RBCs will destroy in spleen or bone marrow. It leads to anemia.

Laboratory diagnosis of Beta thalassemia

  • In physical examination, some may have chipmunk appearance in the face. Hair-on-end appearance can appear on the X-ray of the skull. (Radiological finding) Beta thalassemia can be usually diagnosed using Hb electrophoresis.
  • FBC – Low RBC
  • Blood – picture – Target cells can be seen
  • Hb is low
  • Hb electrophoresis – increased HbF
  • Alkali denaturation test – Increased HbF

Alpha Thalassemia

Alpha thalassemia means, reduced the production of normal Alpha globin chains.

Genetic basis of Alpha thalassemia

There are 4 genes for Alpha chains of the Hb. Alpha thalassemia occurs due to gene deletion

  • 1 gene deletion; asymptomatic
  • 2 gene deletion; 2 genes are deleted in the same chromosome, It is called cis-deletion and 2 genes are deleted in the different chromosome, It is called trans-deletion
  • 3 genes deletion; reduce the production of Alpha containing Hb. It is very severe. It called HbH(Beta4)
  • All 4 genes deletion; It called Barts Hb (Alpha 4) non-functional. These babies will die.

Treatment of thalassemia

  • Iron chelating therapy
  • Regular folate supplement
  • General health care & life style
  • Splenectomy
  • Blood transfusion



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