Which of the given blood cells is irregularly shaped in people affected with sickle cell disease?

Red blood cells are also known as RBCs, red cells, red blood corpuscles, haematids, erythroid cells or erythrocytes. In humans mature red blood cells are oval and flexible biconcave disks. They lack a cell nucleus and most organelles to accommodate maximum space for haemoglobin. Sickle cell disease is an inherited disorder in which red blood cell is abnormally shaped. This abnormality can result in painful episodes, serious infections, chronic anemia and damage to body organs.