HbA Is More Effective Than HbF for Improving the Clinical Course in Sickle Cell Disease.

It is well known that high levels of HbF exert a protective effect on the clinical outcome of sickle cell disease. For this reason hydroxyurea, a drug that increases levels of HbF, is standard treatment for sickle cell disease patients with severe clinical courses. We present, herein, two groups of patients with sickle cell disease (HbS / β thalassemia) with differing genotypes who present similar quantities of HbS, but who clearly have differences in the amounts of HbF and HbA. The table below presents the genotypes, and the hematological and clinical data of the two groups of patients. Data presented in the table demonstrate that the clinical course of the patients with a high percentage of HbA is very mild, whilst the clinical course of the patients with high levels of HbF is severe. It is important to note that the amount of HbA + HbF is not statistically different in the two groups (22.8±8.3 e 28.1±1.8). There were no other factors, such as haplotypes or α genotypes that could have interfered with the clinical presentation of the patients. Taken together, the data presented suggest that a protection against hemoglobin S polymerization in patients may be more effective in the presence of HbA compared to similar amounts of HbF. In this case, it would be possible to speculate that a therapy aiming to induce the production of HbA, even in small amounts, may be more effective in the treatment of sickle cell disease than the increase in the production of HbF.