Sickle cell disease is a group of disorders that affects hemoglobin, and causes distorted sickle- or crescent- shaped red blood cells. It is a genetic disease acquired by the inheritance of two abnormal hemoglobin S genes (HbS), one from each parent. SCD is most common among people from Africa, the Caribbean, India, the Mediterranean and the Middle East in relation to its survival advantage against malaria. And it is estimated that about 3.2 million people have sickle-cell disease worldwide.
A person inheriting a single copy of the defective gene does not usually display any symptoms and is said to have sickle-cell trait. Traditionally the condition is believed to be benign. Nonetheless, several potentially significant complications have been increasingly described in the literature including urinary tract infection in women, hyphema complications, splenic infarction related to altitude, venous thromboembolism and sudden death in athletes.