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DR Medhat MRCP

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II.Thalassemia<br />

- It`s an inherited autosomal recessive heterogenous group of Hb disorders result from<br />

reduced or absent synthesis of one or more of polypeptide chains of normal globin<br />

molecule of Hb→↓ Hb synthesis (microcytic hypochromic) & formation of abnormal Hb<br />

molecule.<br />

• Normal Hb structure :<br />

- Hb molecule is composed of :<br />

1) 4 heme molecules ( each is formed of Fe atom + 4 porpyrin molecules).<br />

2) 1 globin molecule which is formed of 4 polypeptide chains ( i.e tetramer )each<br />

chain is formed of 140 aa according to their arrangement the chains are named.<br />

3) According to the type of globin chains in , adult Hb is classified into 3 types :<br />

Hb-A .<br />

Hb- A2.<br />

Hb-F<br />

6

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