Sickle Cell Disorder is a hereditary haemoglobin disorder which occurs when a person inherits two abnormal copies of the haemoglobin gene, one from each parent. This is a lifelong ailment characterized by premature breakdown of rigidly sickled red blood cells causing, in the case of HbSS, constant anaemia and occlusion of small blood vessels, which is believed leads to pain crises and other manifestations.