Although SCD is most commonly caused by the homozygous inheritance of HbS (HbSS), it can also result from the coinheritance of HbS with other mutations of the HBB gene, most notable among them being a second structural haemoglobin variant, HbC, and β-thalassaemia, a condition characterized by the reduced production of normal β-globin chains [3]. The gene discussed is HBB; the disease is Schnyder corneal dystrophy.