Sickle-Cell Anaemia

Sickle-Cell Anaemia, also sickle-cell disease, hereditary condition in which haemoglobin, an oxygen-carrying protein in the blood, is altered, leading to periodic interruptions in blood circulation. The disease is found predominantly in blacks; it also occurs in the Middle East and the Mediterranean area.

Symptoms of the condition appear at about six months of age and may include enlargement of the abdomen and heart and painful swelling of the hands and feet. In adolescence, sexual maturation may be delayed. The disturbances in blood flow associated with the disease also dispose affected people to infections and leg ulcers. These symptoms are due to the altered haemoglobin, which changes shape when the amount of oxygen in the blood is reduced for any reason. The red blood cell in which the haemoglobin is contained also changes its shape, from round to crescent (sickle shaped). The sickle-shaped red cells interfere with normal blood flow by plugging up small blood vessels.

Sickle-cell anaemia occurs when an individual inherits a sickle-cell gene from each parent. Programmes have been initiated to detect carriers of the gene, who do not themselves show the trait. Such carriers are informed that a child resulting from the union of two carriers runs a one-in-four risk of having sickle-cell disease.

Therapy for sickle-cell anaemia is largely to allay symptoms. Preventive administration of penicillin to affected children by the age of four months greatly decreases mortality from infections. For this reason, routine screening of newborns for sickle-cell anaemia is currently carried out in most developed countries.