Berg et al (1991) have previously identified HMG-Y and HMG-1 protein which bind and bend the DNA at or near the BP1 binding site within the β globin gene promoter and facilitate the binding of BP1 and other repressor proteins in this region.25 Therefore BP1 and HMG protein may be important mediator proteins of β globin expression affecting the presentation of Sickle cell disease, β thalassemia and the HPFH phenotype. This evidence concerns the gene PROS1 and sickle cell disease.