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Question
Give a detail account of thalassemia.
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Solution
- Thalassemia is an autosomal, inherited recessive disease.
- A haemoglobin molecule is made of four polypeptide chains- 2 alpha (α) and 2 betas (β) chains.
- The synthesis of alpha chains is controlled by two closely linked genes (HBA1 and HBA2) on chromosome 16 while the synthesis of the beta chain is controlled by a single gene (HBB) on chromosome 11.
- Depending upon which chain of haemoglobin is affected, thalassemia is classified as alpha-thalassemia and beta-thalassemia.
- It is caused due to deletion or mutation of a gene that codes for alpha (α) and beta (β) globin chains that result in the abnormal synthesis of haemoglobin.
- Symptoms: In Thalassemia, the person shows symptoms like anemia, pale yellow skin, change in size and shape of RBCs, slow growth and development, dark urine, etc.
- Massive blood transfusion is needed for these patients.
- Thalassemia differs from sickle-cell anemia. Thalassemia is a quantitative problem of synthesizing few globin molecules, while sickle cell anemia is a qualitative problem of synthesizing an incorrectly functional globin.
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Given below is the representation of amino acid composition not the relevant translated portion of β-chain of haemoglobin, related to the shape of human red blood cells
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