Write short notes on the following.
Thalassemia

Explanation

Thalassemia It is an inherited blood disorder in which an abnormal form of haemoglobin is formed in the body. Thalassemia commonlyy occurs in three forms, i.e. `alpha`-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 haemoglobing-H disease and hydrops fetalis.
The latter is more severe and expressed when all four globin genes are mutated.
`beta`-thalassemia has 2 subtypes Coeley.s anaemia (thalassemia major) 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 `beta`-globin.