The primary causes of sickle cell anemia (SCA), also known as sickle cell disease (SCD), are largely due to a genetic mutation in the body's hemoglobin, specifically in chromosome 11. Other causes of sickle cell anemia involve genetic inheritance of the disease. Children of two individuals with SCA generally are born with the disease, while those with one parent suffering from SCA typically do not experience any notable symptoms. The causes of sickle cell anemia are also related to problems with the blood, such as dehydration, low oxygen levels, and increased acidity.
Causes of sickle cell anemia can be attributed to a mutation in hemoglobin, the iron-rich compound that gives blood its red coloring. Under normal circumstances, red blood cells are disc-shaped and full as a result of the presence of glutamic acid. The mutation that causes SCA occurs in the beta-globin gene, which, in turn, causes the glutamic acid to be replaced with valine. The chemical change causes red blood cells to become rigid, sticky, and deformed, similar in shape to a crescent moon.
The genetic causes of sickle cell anemia are passed on to the next generation through a pattern called autosomal recessive inheritance. This means that both parents should pass the gene for the child to inherit the disease. If only one parent carries the mutation, the child will have what researchers call the "sickle cell trait."
Individuals with the sickle cell trait possess both normal and mutated hemoglobin and could potentially pass SCA on to their children. The sickle cell trait does not exhibit any symptoms outside of a number of sickle-shaped blood cells, however, and is considered harmless to the patient. With every pregnancy, two parents who each have the sickle cell trait have a 25% chance of producing a healthy child, a 50% chance of producing a carrier child, and a 25% chance of producing a child without a blood cell mutation.
Causes of sickle cell anemia are also connected to certain physical conditions. The distortion of the red blood cells in individuals with the mutation is generally triggered by low blood volume. Other contributing factors include dehydration, low blood oxygen levels, and increased blood acidity. Blood cell sickling in individuals with the sickle cell trait is also believed to be connected to high metabolic activity. Pregnant women are considered more prone to cell sickling due to the increased activity in the uterus and hormonal imbalances.