Sickle cell anemia

Sickle hemoglobin (HbS), so called because of the sickle shape it imparts to deoxynated red cells, is responsible for a wide spectrum of disorders that vary with respect to degree of anemia, frequency of crises, extent of organ injury, and duration of survival. The sickle mutation substitutes thymine for adenine in the sixth codon of the beta-gene (GAG -> GTG), thereby encoding valine instead of glutamine in the sixth position of the beta-chain. This ostensibly minor change in structure is responsible for profound changes in molecular stability and solubulity. The tendency of deoxynated HbS to undergo polimerization underlies the innumerable expressions of the sickling syndromes. (Turk Arch Ped 2009; 44 Suppl. 39-42)