Sickle cell anemia is a blood disease in which the red blood cells possess an abnormal crescent or sickle shape, when observed under microscope. It is an inherited disorder and is attributed to a single base substitution in the DNA sequence of the gene encoding the beta chain of hemoglobin. The sickle cell trait protects against malaria. In the sickled RBC, malaria parasites can not survive, thus giving advantage to the anaemic patients.So, the correct answer is 'Sickle cell anaemia'