The condition is asymptomatic, and is only noticed when screening for other hemoglobin disorders. Sickle cell disease In persons with sickle cell disease, high levels of<unk>  hemoglobin as found in a newborn or as found abnormally in persons with<unk> , the HbF causes the sickle cell disease to be less severe. In essence the HbF inhibits polymerization of HbS. A similar mechanism occurs with persons who have sickle cell trait. Approximately 40% of the hemoglobin is in the HbS form while the rest is in normal HbA form. The HbA form interferes with HbS polymerization.
Hereditary persistence of fetal hemoglobin
Paroxysmal nocturnal hemoglobinuria
Paroxysmal cold hemoglobinuria
Beta thalassemia
Neonatal alloimmune thrombocytopenia
Congenital hemolytic anemia
Gestational thrombocytopenia
Hemoglobin Lepore syndrome