Hemoglobin S Sickle Cell Disease (Hb S)
- Method:
- Anticoagulant:
- Recommendation:
- Method:Blood Count
- Anticoagulant:EDTA*
- Recommendation:obligatory
- Method:Hemoglobin Differentiation
- Anticoagulant:EDTA*
- Recommendation:obligatory
- Method:Iron Status
- Anticoagulant:Serum**
- Recommendation:obligatory
- Method:Molecular genetics
- Anticoagulant:Serum**
- Recommendation:once
*3 ml EDTA-Blut (Blutbildröhrchen), **7,5 ml Serum, ***7,5 ml EDTA-Blut (extra Röhrchen)
Hemoglobin S (Hb S; sickle cell disease): Overview
Sickle cell disease includes all hemoglobinopathies caused by abnormal hemoglobin S (Hb S). This includes homozygous HbSS forms as well as Hb S in compound heterozygous form with other β-globin gene mutations. The most common of these are Hb S-β-thalassemia and Hb SC disease. Far less frequently, other compound heterozygous combinations occur, such as HbSD, HbSOArab, HbSLepore, and HbSE. Genetically, Hb S is based on an amino acid exchange at position 7 of the β-globin chain (HBB:c.20A>T p.Glu7Val, HbVar ID 226).
Typically, carriers of hemoglobin S and patients with sickle cell disease come from Africa, countries of the Eastern Mediterranean, Iraq, the Arabian Peninsula, India, North and South America and the Caribbean. It is estimated that there are over 3,000 patients with sickle cell disease in Germany (as of 2017), and since 2021, screening for sickle cell disease has been a part of newborn screening in Germany.
The clinical course is determined in part by the genetic constellation, with patients with HbSS, HbS-β0-thalassemia, HbSD, and HbSOArab showing the most severe course. The cause of the symptoms is the decreased elasticity and sickle-like deformation of the erythrocytes, due to the altered hemoglobin structure and the altered properties of hemoglobin S in the deoxygenated state. As a result, hemolysis and vascular occlusion-related crises occur, which determine the disease pattern of sickle cell disease. Thus, indications for testing for sickle cell disease include the following:
- Hemolytic anemia (normocytic or microcytic, depending on the genotype present).
- Recurrent pain crises, especially in the skeletal system
- Pronounced anemia, possibly shock symptoms, and pronounced splenomegaly
- Pronounced anemia and absent reticulocytosis
- Unclear painful swellings of hands and feet in young children
- Aseptic necrosis of femoral or humeral head
- CNS hemorrhage or infarction
- Unexplained severe infection
- Positive family history
Carriers of the hemoglobin S sickle cell disease (Hb S) usually have no blood count abnormalities or clinical symptoms. Exceptions include papillary necrosis with painless hematuria in up to 4% of Hb S carriers during life, painful splenic infarcts with vigorous exercise or dehydration at high altitudes, and the very rare renal medullary carcinoma.
Hemoglobin S (Hb S; sickle cell disease): Diagnosis
The diagnosis or exclusion of sickle cell disease or Hb S carrier status is made by a combination of blood count, iron status (in the presence of hypochromia and/or microcytosis), hemoglobin differentiation and molecular genetic testing in the case of abnormal findings to confirm the diagnosis.
Hemoglobin S (Hb S; sickle cell disease): Therapy
Newborn screening and early treatment as well as new treatment options have significantly improved the prognosis of sickle cell disease.
The treatment of sickle cell disease depends on the acute and chronic symptoms.
Current recommendations and guidelines on therapy can be found at:
AWMF: https://www.awmf.org/leitlinien/detail/ll/025-016.html
Onkopedia: https://www.onkopedia.com/de/onkopedia/guidelines/sichelzellkrankheiten/
Status: April 2024