Write notes on any two of the following
Thalassemia

Explanation

Thalassemia
It is an inherited blood disorder in which an abnormal form of haemoglobin is formed in the body. Thalassemia commonly occurs in three forms, i.e. `alpha`-thalassemia, `beta`-thalassemia and thalassemia minor.
`alpha`-thalassemia is caused by a pair of defective alleles regulating the synthesis of `alpha`-haemoglobin. It is further classified into two types-haemoglobin-H disease and hydrops fetalis.
The latter is moreisevete and expressed when all four globin genes are mutated. The affected babies are either stillborn or die shortly after birth. Haemoglobin-H disease occurs when 3 out of 4 `alpha`-globin genes are mutated.
`beta`-thalassemia has 2 subtypes Cooley.s anaemia (Thalassemia major) and thalassemia intermedia. Thalassemia major is more severe while thalassemia intermedia is less severe. Thalassemia major is expressed when `2beta`-globin genes are absent are mutated. It occurs when body is unable to produce `alpha` -globin.