The Power of Your Choice
Your choice of the IHTC Pharmacy Program directly supports your IHTC team and patient services, and activities provided to the hemophilia community. The IHTC Pharmacy Program provides savings to you and your health insurance plan.
Every patient has the right to choose their clotting factor pharmacy provider. The IHTC supports your right of choice and will assist you in making an informed decision.
Simple Facts about Sickle Cell
Sickle cell disease is the most common hereditary hematologic disorder in the world. It primarily affects Black Africans and Americans, as well as some persons of Mediterranean, East Indian or Latin American heritage. About 8% of the African-American population carries the sickle cell trait. Sickle cell disease affects about 1 in 400 African-Americans. In the USA there are some 50,000 African-Americans and Hispanics affected with sickle cell disorders.
Sickle cell disease is a generic term for a group of genetic disorders characterized by a predominance of hemoglobin S (Hb S). These disorders include sickle cell anemia, the sickle beta thalassemia syndromes, and the hemoglobinopathies in which Hb S is associated with another hemoglobin that participates in the polymerization of hemoglobin and the sickling of the red blood cells. Examples include hemoglobin SC disease, hemoglobin SD disease and hemoglobin SOArab disease.
Normal hemoglobin, Hemoglobin A contains two alpha and two beta globin chains. In sickle hemoglobin, the alpha chains are normal, but the beta chain has a substitution of valine for glutamic acid in the sixth position. This substitution results in the susceptibility to shape distortion and sickling. This occurs when the cell is deoxygenated and polymerizes, forming microtubules (rod-like structures) rendering it rigid and fragile. When re-oxygenated, the cells can initially resume a normal biconcave shape, but after repeated cycles of “sickling and unsickling” the erythrocyte is permanently damaged and hemolyzes. The hemolysis results in chronic anemia, usually accompanied by some degree of accelerated reticulocytosis. The change in the shape of the red cells is not solely responsible for hemolysis, tissue damage, or infarction. It is now understood that that there are many other contributing factors, such as changes in neutrophils, endothelial cells and platelets, as well as release of inflammatory cytokines.
All sickle cell disorders involve an inherited gene for sickle hemoglobin from one or both parents.
Sickle cell trait is not considered a disease. The gene for sickle hemoglobin is inherited from one parent and the gene for normal hemoglobin from the other resulting in the carrier state (AS).
Sickle cell hereditary persistence of fetal hemoglobin is likewise not considered a disease and is not associated with clinical problems.
Sickle cell diseases include inheritance of the gene for sickle hemoglobin from one parent and one of the following:
- A gene for sickle hemoglobin from the other parent (Hb SS),
- A gene for another abnormal hemoglobin from the other parent (Hb SC, HbSD Punjab, HbSO Arab, HbS Leopore, or Hb SE),
- A gene that limits hemoglobin production from the other parent (sickle beta +/0 thalassemia). In S beta (+) thalassemia there is some production of beta globin, and in S beta (0) thalassemia there is no production of beta globin.
All of these conditions are accompanied by health problems.
A patient with a sickle cell disorder can also inherit an alpha gene abnormality. Deletion of two of the four alpha genes may occur in persons of African descent and result in alpha thalassemia trait.
Complications of sickle cell disorders result from the inability of the rigid cells to pass uneventfully through the microvasculature. The changes occurring in the red blood cells lead to hypoxia of the tissues and potential or actual tissue damage. Most commonly, this is manifested clinically as the onset of the acute sickle cell painful vaso-occlusive episode.
Macrovascular occlusion may also occur, such as cerebral arterial thrombosis (stroke), usually in children with Hb SS disease. Ischemic stroke can affect adults and children with other genotypes such as Hb SC and S beta 0 thalassemia.
Other complications of sickle cell disease include splenic infarction, splenic sequestration, and increased risk of infection.
Adults have progressive end-organ damage, particularly of the lungs and kidneys, and there are increased risks during pregnancy.
All of the manifestations associated with sickle cell disease (Hg SS) can occur in sickle cell hemoglobin C and sickle cell b thalassemia. Patients with Hg SC disease and Hg Sb thalassemia tend to have a milder clinical course, with the exception that eye disease and avascular necrosis of the hip are more common in those groups.
Patients with sickle cell disease and their families must cope with the impact of repeated and unpredictable pain episodes, chronic pain, chronic anemia and easy fatigue which cause absenteeism from school and work, hospitalizations, and fear of early death. There is no consistently effective, widely acceptable treatment for sickle cell disease. The prognosis is uncertain and complications are variable and often not measurable (as in vaso-occlusive pain). Complications are often inadequately managed due to attitudes among health care workers and their unfamiliarity with the disease.
Appropriate management begins with definitive diagnosis by hemoglobin electrophoresis. Treatment requires a multi-disciplinary approach with adequate therapy for pain, infections, other acute complications, as well as attention to psychosocial and spiritual needs.