HbSD, HbSE, and HbSO


    Rare types of sickle cell disease (SCD). People who have these forms of SCD inherit one sickle cell gene (“S”) and one gene from an abnormal type of haemoglobin (“D”, “E”, or “O”). Haemoglobin is a protein that allows red blood cells to carry oxygen to all parts of the body. The severity of these rarer types of SCD varies. (Source: CDC)