Sickle cell disease

general term that includes several sickling disorders, i.e. disease states that result from the propensity of the red blood cells to change shape

Description
Abnormal forms of hemoglobin, so-called sickle hemoglobins (HbS or Hgb S), polymerise upon deoxygenation, leading to a change in the shape of erythrocytes to sickle or banana shape. These altered erythrocytes may cause painful vasoocclusive crises (by blocking smaller blood vessels), leading to ischemia and infarction, and may damage inner organs, leading for instance to stroke. Sickle cell disease (SCD) includes several syndromes of variable clinical severity (such as Hb SS, Hb SC, Hb S &beta;+-thalassemia, Hb S &beta;0-thalassemia, S/D, S/OArab, S/HPFH). Sufferers have a reduced life expectancy and are most commonly persons with ethnic origin in malaria regions, where the heterozygous form of the disease, imposing very mild sickle-cell disease symptoms whilst giving relative resistance to the malaria parasite, confers a survival advantage (the so-called heterozygote advantage).