This document summarizes beta thalassemia, a genetic blood disorder caused by a decreased production of the beta globin chain. It discusses the molecular defects that can cause beta thalassemia, resulting in reduced or unstable beta globin mRNA. It describes the clinical features of beta thalassemia major, also known as Cooley's anemia, which is characterized by severe anemia and other complications if not treated with regular blood transfusions. It provides information on some common lab findings in beta thalassemia and differences in hemoglobin levels between different types.

1. بسمه تعالی

3. Beta thalassemia Thalassemia: globin chain usually have normal structure but the production are decreased. Beta thalassemia refers to decrease production of beta chain. There is deficit of hemoglobin tetramer in the RBC & usually MCV & MCH are reduced.

4. Molecular defect In beta thalassemia there is considerable heterogenity in molecular defect. 197 different mutation have been identified as the cause of beta thalassemia. Most of associated with single base substitution that produce defects in promotor,RNA processing,slicing or translation resulting in decreased or unstable mRNA. Desite this diversity 20 common mutation accont for %80 of beta thalassemia.

5. In beta * talassemia beta chain synthesis is absent because the related mRNA is absent or is non-functional. In beta+ thalassemia beta chain is resent but reduced in quantity because the related mRNA is decreased or unstable. The terms thalassemia majore , intermedia & minor refer to clinical severity & are not genetic designation.

6. Cooley”anemia Absense or marked decreased in beta chain production (Beta*or Beta+). There is an excess of alpha chain. Aggregation of alpha chain is unstable & precipitate in the normoblast or RBC & damaged the cell. There is ineffective erythropoiesis & a severe hemolytic anemia.

7. Clinical feature Jaundice, splenomegaly, promineat frontal bone. Cortex of the long & flat bone are thin. Extra BM hyerplasia. Most patient require regular transfusion. Major cause of death is cardiac failure due to myocardial sidrosis.

8. blood The anemia is hypochromic & microcytic. Poikilocytosis,target cell ,ovalocytosis ,cabotring,howell-jolly body. The reticulocyte count is less elevated than expected. OF ,sFe ,indirect bilirubin

9. B.M Marked normoblastic hyperplasia. Intramedulary destruction of hemoglobin Iron storage , sidroblast

10. Beta* thalassemia: - Hb A is absent , Hb F is as high as%98 ,Hb A2 is %2 . beta+ thalassemia: - Hb A is present ,Hb F:60-95% ,Hb A2 N or Thalassemia intermedia :in black people with Beta+ Thalassemia ,the clinical feature are less severe & trnsfusion is usually unnecessary. -Hb F:20-40% ,Hb A2:2-5% ,the level of HbA is high

11. Cooley”trait Beta chain synthesis is reduced. There are usually no symptoms or abnormal physical signs. MCV ,MCH ,MCHC N or ,Retic ,OF HbA2:3.5-7% ,HbF:1-3%

12. Iron deficincy & cooley”s trait Increased in RBC count with decreased MCV Thalassemia trait The MCV/RBC ratio<13 thalassemia trait The MCV/RBC ratio>13 iron deficincy