hemoglobin S
Also written as: HbS — hemoglobin S
Abnormal hemoglobin variant causing sickle cell disease when present in homozygous form (HbSS).
Full Definition
Hemoglobin S (HbS) is a variant hemoglobin resulting from a single amino acid substitution (glutamic acid to valine) in the β-globin chain. When deoxygenated, HbS polymerizes, causing red blood cells to assume a characteristic sickle shape. In homozygous form (HbSS), it causes sickle cell disease, while heterozygous individuals (HbAS) have sickle cell trait. The presence of HbS can be detected through hemoglobin electrophoresis or high-performance liquid chromatography. Understanding HbS levels is crucial for disease management and genetic counseling.
Usage
Usage note: Use HbS after first mention. Always specify percentage when reporting laboratory values.
In Context
- "Newborn screening detected 85% hemoglobin S, confirming sickle cell disease." — Laboratory report
- "The child inherited hemoglobin S from one parent and hemoglobin C from the other." — Genetic counseling note