Sickel cell disease is a group of disorder that affects haemoglobin , the molecule in red blood cells that delivers oxygento cells throughout the body.

People with this disorders have typical haemoglobin molecules called haemoglobin S , which can distort red blood cells into sickle or crescent shape.

This small defects in beta globin gene causes a problem in the beta globin part of haemoglobin , changing the way that heamoglobin works.