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Medical Term:

hemoglobin S


Definition: an abnormal Hb with substitution of a valyl residue for a glutamyl residue at the sixth position of the β chain; the formula is α22S, or, more specifically, α226Glu→Val. Heterozygous state: sickle cell trait, no anemia, Hb S 20–45% of total, the rest Hb A. Homozygous state: sickle cell anemia, Hb S 75–100% of total, the rest Hb F or Hb A2.

Synonym(s): sickle cell hemoglobin