HBB and sickle cell disease: Homozygous sickle cell anaemia (SCA) also called HbSS, is a form of sickle cell disease that results from single amino acid substitution (Val for Glu) at the sixth position in each of the two beta globin chain of haemoglobin (α2βs2) and has remained a non-infectious disease of high morbidity and mortality world wide particularly in black populations, Asia and Mediterranean countries [1].