Sickle cell disease SCD is an autosomal recessive disorder that causes a mutation of GAG GTG glutamine to valine at the sixth position of the β globin chain of haemoglobin A HBA which consequently mutates into haemoglobin S HbS https www ncbi nlm nih gov pmc articles PMC3766347 bibr16 2040620713483063 SCD occurs when an offspring inherits abnormal haemoglobin S gene from both parents The parents of an individual with an autosomal recessive condition carry either one or two copies of the mutated gene known as the sickle cell trait however the carrier typically does not show any signs and symptoms of the disorder Manifestation of SCD arises due to HbS polymerising under deoxygenated environment as HbS attaches to β globin molecules resulting in highly ordered molecular polymers causing red blood cells to deform into crescent shape Deformed RBC cause clinical complications as cells can stick to vessel walls thus obstructing blood flow causing painful vaso occlusive complications stroke avascular necrosis pulmonary hypertension infections renal failure and thrombosis