What is Sickle Cell Anemia?

I was told by my doctor I am at risk for having a child with sickle cell anemia. Please tell me more about this condition. A concerned mother, Greenwood, SC

Sickle cell anemia (SCA) is one of many types of disease that can affect the oxygen carrying molecule in the red blood cells, hemoglobin. This protein gives blood cells there characteristic red color and round shape, making travel through the blood vessels easy. Red blood cells in persons with SCA are "crescent moon" shaped and stiff, with oddly pointed ends. These pointed ends can cause the blood cells to jam and accumulate within the smaller blood vessels of the body. This plug of red blood cells leads to the complications of sickle cell disease.

Medical complications from SCA are numerous and quite variable between individuals. Pain episodes or sickle cell "crises" are a regular feature of this condition, and result from the clumping of sickled red blood cells in tiny blood vessels throughout the body. Inflammation (swelling) occurs, affecting the joints, back, stomach, hands and feet, and may lead to stroke in more severe cases. Moreover, a lack of oxygen to the tissues increase the pain and damage to these areas. These crises may last from hours to days, many times requiring hospitalization. People with SCA also have fewer red blood cells than normal.

Red blood cells normally have a life span of approximately 120 days. Sickled red blood cells tend to deteriorate faster, lasting only from 10 - 60 days, leading to a chronic anemia (low blood). The destroyed blood cells in the body fluids can make the urine look darker and cause a yellowish color to the whites of the eyes (jaundice). If the blood count falls very low, a blood transfusion may be needed. Individuals with SCA are also more prone to recurrent infections and spleen problems, gallstones, poor appetite and delayed growth.

SCA is an inherited autosomal recessive condition. Most individuals carry two copies of the working gene (A,A) for normal hemoglobin production on chromosome 16. Individuals with SCA have inherited two copies of the non-working (S,S) gene and cannot produce normal hemoglobin. Carriers of SCA, also described sometimes as having sickle cell trait, have one working (A) copy of this gene and one non-working (S) copy. Sickle cell carriers (A,S) many times do not know they carry the non-working (S) gene because it causes very few medical or health problems. However, if both parents in a pregnancy are known sickle cell carriers (A,S), there is a 25% (1 in 4) chance that both will pass on their non-working (S) copy of this gene and have offspring with SCA. Likewise, carrier parents (A,S) have a 50% chance their offspring will be carriers (A,S) like themselves, and finally a 25% chance that their offspring will inherit both working (A,A) gene copies for hemoglobin. About 1 in 12 African-Americans are carriers for SCA. It occurs less often in other races. For further information please call the American Sickle Cell Anemia Association at (216) 229-8600.