Sickle Cell Disease (S/S and S/C) and Other Hemoglobinopathies
Sickle cell disease is inherited in an autosomal recessive pattern. Normally a person has two HBB genes that produce Hgb A. In people with sickle cell disease, both HBB genes have a mutation and they only produce abnormal hemoglobin (Hgb S only or Hgb S and Hgb C). Each parent of a newborn with sickle cell disease has sickle cell trait (one gene that produces Hgb A and one gene that produces abnormal hemoglobin, like S or C). When both parents have sickle cell trait, the chance of their newborn inheriting two mutated genes is 25%.
The sickle cell trait does not usually cause health problems. Most people with sickle cell trait go through life without knowing they have it. In very rare instances, the blood cells in people with sickle cell trait can take on a sickle shape during times of extreme stress on their body (deep sea diving, mountain climbing, surgery) and then they may have symptoms.
Sickle cell disease is a serious medical condition. Symptoms usually start in childhood. The first symptom in most children is pain and swelling of the hands and feet. There is also a risk for severe infections. Over time, the sickle shaped red blood cells get stuck in the blood vessels and cause chronic pain and problems with the organs including the liver and spleen. People with sickle cell disease may also have a shortage of red blood cells, known as anemia, which can cause them to be pale, short of breath and tire easily. Chronic anemia can also cause delayed growth and development.
- Incidence: The incidence of sickle cell disease is different for each ethnic group. It is most common in African Americans with an incidence of 1 in 500.
- New York State Method of Screening (First Tier): Screening for sickle cell disease is accomplished by high-performance liquid chromatography (HPLC).
- Testing can be affected by: Transfusion of red cells can cause a false negative result.
- Interpretation/reporting of data: Results are reported as within acceptable limits, evidence of a transfusion or as a referral. A repeat specimen should be collected 4 months after the most recent transfusion for infants that had a blood transfusion. For infants that are referred, the result is reported as a list of the hemoglobins identified on HPLC. For example, an infant with sickle cell disease is reported as hemoglobin F (fetal) and hemoglobin S (sickle) and no hemoglobin A (adult).
- Referral to Specialty Care Center: Patients with an abnormal newborn screen for sickle cell disease are referred to a Specialty Care Center for evaluation by a hematologist trained in the diagnosis and treatment of sickle cell disease.
| Screened Hemoglobinopathies: | Hb S trait (sickle cell trait) Hb C trait Hb D trait Hb E trait Hb SS disease (sickle cell disease) / Hb S Beta thalassemia Hb SC disease (sickle C disease) Hb SD disease (sickle D disease) Hb SE disease (sickle E disease) Hb CC disease / Hb C Beta thalassemia Hb DD disease / Hb D Beta thalassemia Hb EE disease / Hb E Beta thalassemia |
| Hemoglobinopathies reported when detected incidentally: | Hb variant trait Hb variant disease Hb disease (e.g., SS disease) with possible variant present |
| Not screened for: | Alpha thalassemia trait Beta thalassemia trait |
Diagnostic testing may include cellulose acetate electrophoresis, HPLC and genetic testing of the HBB gene.
There is not a cure for sickle cell disease. Adequate rest and hydration, immunizations and a medication, hydroxyurea, can significantly reduce the complications of sickle cell disease. Treatments may include blood transfusions and antibiotics. Pain management includes supportive measures like massage, intravenous fluids and pain medication. As the disease progresses, interventions like removal of the spleen or kidney transplant may be needed.
Prognosis is variable and dependent on multiple factors including the severity of disease and response to treatments.
Sickle cell disease (S/S and S/C) is a genetic disorder of the blood. Red blood cells bring oxygen from the lungs to every part of the body. Oxygen is stored in the red blood cell by hemoglobin (Hgb). There are several different types of hemoglobin. Normal hemoglobin is called Hgb A and the sickling type is called Hgb S. A person with sickle cell disease has no Hgb A and the red blood cells have an abnormal shape. Instead, they only have Hgb S or a combination of other hemoglobins, like Hgb C. In addition to sickle cell disease, there are many other types of hemoglobin disorders, some of which can also be detected by the newborn screen.