It occurs due to an autosomal recessive gene, that expresses in homozygous condition.
Two carrier or heterozygous parents can produce an affected child.
This genetic defect originated in Mediterranean region due to mutation or deletion in the genes controlling the synthesis of globin chains of Haemoglobin. It also occurs in the middle east, Indian subcontinent & South East Africa.
It is a Quantitative Inheritance.
Adult hemoglobin is a heterotetramer.
It consists of four polypeptide chains, 2 α & 2 β types.