Which chromosomes carry the mutant genes causing thalassaemia in humans ? What are the problems caused by these mutant genes ?

Thalassemia is an inherited disorder wherein the body produces an improper form of haemoglobin. There are of two types Alpha and Beta thalassemia.

Most people affected by beta thalassemia have mutations in both copies of HBB gene in each cell, while in alpha thalassemia the mutations in two different genes HBA1 and HBA2 are associated.

Problems caused are as follows:

_• Beta thalassemia symptoms generally appear before child’s second year of age and severe anaemia concerned with this condition can be fatal. This needs frequent blood transfusion.

_• Alpha thalassemia consists of major forms namely, Hydrops fettles and Haemoglobin H disease.

_• Haemoglobin H can be responsible for bone complexities. The forehead, cheeks and jaw may overgrow. It can also cause enlarged spleen and malnourishment.