Unstable hemoglobins
- 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:EDTA***
- Recommendation:obligatory
*3 ml EDTA blood (blood count tube), **7.5 ml serum, ***7.5 ml EDTA blood (extra tube)
Unstable Hemoglobins: Overview
Unstable hemoglobins are hemoglobin variants that lead to clinically relevant hemolysis due to their structural changes. Primarily, unstable hemoglobins are variants in the α- and β-globin chains. Occasionally, unstable hemoglobins caused by variants in the γ-globin chains have also been described, leading to hemolysis in neonates. Unstable hemoglobins due to δ-globin chain variants have also been described but do not cause clinically relevant hemolysis because of the small contribution of HbA2 to total hemoglobin. Most unstable hemoglobins cause relevant hemolysis in the heterozygous state, and homozygous variants of unstable hemoglobins have been described only in isolated cases.
To date, more than 135 unstable hemoglobin variants have been described, of which Hb Köln is the most common. Causes for the formation of unstable hemoglobins are different genetic alterations such as single base variants, deletions or tandem duplications of codons in a globin gene or variants in the stop codon of HBB.
Unstable hemoglobins: Diagnostics
Detection of unstable hemoglobins is made by a combination of blood count, iron status, hemoglobin differentiation, and molecular genetic testing. Since not all variants of unstable hemoglobins are visible in hemoglobin electrophoresis, molecular genetic methods are regularly used when the presence of unstable hemoglobins is suspected.
Unstable hemoglobins: prognosis
The clinical picture depends on the type of unstable hemoglobin. Infections and the use of oxidative drugs may promote hemolysis in the presence of unstable hemoglobin.
Status: April 2024