A child suffering from thalassemia is born to a normal couple. But the mother is being blamed by the family for delivering a sick baby. (a) What is thalassemia?

Thalassemia is an inherited blood disorder which can occur due to deletion of the genes controlling the formation of globin chains (Alpha and Beta) of haemoglobin. It is an autosomal recessive disease meaning two copies of an abnormal gene must be present in order for the disease to develop. (b) The mother cannot be blamed for the disease as it is an autosomal recessive blood disorder. The genes for the synthesis of globin chains are present on autosomes (i) Formation of Alpha chain is controlled by 2 genes present on chromosome 16 and (ii) Formation of Beta-chain is controlled by one gene present on chromosome 11. The disease occurs when the progeny receives defective genes from both the parents (as thalassaemia is expressed in homozygous recessive condition only). (c) Values that can be propagated in families are: (i) One should get themselves checked for the disease before marriage and should be aware of such autosomal diseases. (ii) The manifestation of the disease occurs due to defective genetic set up of both the parent and so the female should not be blamed.