HbSD disease

atypical sickle cell disease, caused by double heterozygosity

Description
In HbSD, one &#946;-globin gene encodes a chain leading to formation of hemoglobin S (HbS) and the other &#946;-globin gene encodes a &#946;-chain leading to formation of hemoglobin D (HbC). Almost equal parts of HbS and HbD are found in the red cells. HbD, unlike the normal adult Hb (HbA), can participate in the polymerization process with HbS, thus leading to atypical hemolytic anemias with enhanced sickling. See also HbSC