THALASSEMIA

It is an autosomal recessive blood disorder which occur due to mutation in the genes responsible for the formation of globin chains of haemoglobin .

Due to this disorder the body produces an abnormal form of haemoglobin which results in excessive destruction of red blood cells and further leads to anemia .

The genes for the synthesis of globin chain are present on autosomes i.e. 1-formation of alpha chain is  controlled by two genes i.e. HBA1 and HBA2 present on chromosome no 16 and 2-formation of beta chain is controlled by one gene HBB present on chromosome no 11

This disorder when the progeny receives defective genes from both the parents as THALASSEMIA is expressed in homozgyous  recessive condition 

there are 2 primary forms of THALASSEMIA 1-ALPHA THALASSEMIA 

                                                                            2-BETA THALASSEMIA 

1-ALPHA THALASSEMIA

Normally each person has four genes for alpha globin 

It occurs when one or more of the gene that control the making of alpha globin is absent of defective .There are four main type of alpha thalassemia 

a. Alpha thalassemia major

b. Alpha thalassemia minor

c. Haemoglobin H disease

d. Silent alpha thalassemia carrer

2-BETA THALASSEMIA

It occurs when there are problems with one or both of the beta globin genes. This is the most common type of thalassemia.

Two genes are involved in making the beta haemoglobin chain . Thus beta thalassemia is of  2 types 

a. Thalassemia major

b. thalassemia minor