Explain thalassemia as an example for Mendelian disorder.

Explanation

(1) This disease is transmitted to the offspring when both the parents are unaffected but carriers for the gene.
(2) The defect is caused due to either mutation or deletion which results in reduced rate of synthesis of one globin chain ( `hata` and `hata`chains) that make up haemoglobin.
(3) This causes formation of abiormal haemoglobin molecule resulting in anaemia.
(4) Thalassemia can be classified according to which chain of the haemoglobin molecule is affected.
(5) In `hata`thalassemia production of `hata` globin chain is affected.
(6) `hata` thalassemia is controlled by 2 closely linked genes `HBA_(1)` and `HBA_(2)` on chromosome 16 of each parent and it is observed due to mutation or deletion of one or more of the four genes. The more genes are affected, the less alpha globin molecules are produced.
(7) `hata` thalassemia is controlled by a single gene HBB on chromosome 11 of each parent and occurs due to mutation of one or both the gene.
[Autosome linked recessive blood disease]