Sickle cell anemia is an inherited blood disorder that is characterized by red blood cells (erythrocytes) that are sickle-shaped due to defective hemoglobin, the vital oxygen-carrying protein inside red blood cells. As outlined in the "Journal of Occupational Medicine," this disease affects every organ and body system and causes varying degrees and types of symptoms in different individuals.
Cause
Sickle cell anemia is a genetic lifelong disease that cannot be prevented and does not have a cure. This disease is caused when a mutant gene called "hemoglobin S" is received from both parents. Individuals who inherit the sickle cell gene from only one parent are sickle cell carriers; they will not have symptoms of the disease but will be able to pass the trait on.
Anemia
Anemia is a blood disorder in which the body has lower than normal levels of healthy red blood cells. In sickle cell anemia, this is due to the defective hemoglobin that causes red blood cells to distort into a sickle shape. Normal red blood cells live for 120 days and are round in shape. The National Heart, Lung and Blood Institute explains that sickle cell anemia causes decreased red blood cell counts because they are more fragile and live for only 10 to 20 days. The bone marrow, which produces new red blood cells, cannot make new ones fast enough, resulting in low red blood cells and decreased iron and oxygen in the body.
Symptoms
As listed by the University of Maryland Medical Center, symptoms of sickle cell anemia include some that are common to other forms of anemia, such as fatigue, tiredness, weakness and an increased heart rate. Sickle cells are stiff and sticky and can form clumps or blockages and narrowing in the blood vessels, leading to heart disease and stroke. Other symptoms include pain in the organs, swelling of the hands and limbs, damage to the spleen, chest pain, infections, skin ulcers, jaundice with yellowing of the eyes and skin, and delayed growth and development, particularly in children.
Malaria Link
As outlined in the journal of the "Proceedings of the National Academy of Sciences (PNAS)," sickle cell anemia may have developed from a genetic mutation thousands of years ago. Malaria outbreaks caused large number of deaths in areas where people were prone to sickle cell anemia. However, individuals with sickle cell anemia or who carried the genetic trait survived the malaria infections. This led to an increased proportion of people with sickle cell anemia in areas such as India, sub-Saharan Africa and the Mediterranean. These individuals survived malaria outbreaks and passed on the sickle cell anemia genes.
Effect on Malaria
It is not yet determined why individuals with sickle cell anemia, particularly young children, are able to resist or survive malaria infections. However, in the study published in the journal of the PNAS, the sickled red blood cells were shown to kill, or lyse, the malaria parasite. This was thought to occur by disrupting the metabolism (energy production) of the parasite. Another explanation is that sickle cells decrease the rate at which the malaria parasites spread throughout the body, allowing the immune system to build defense and attack it effectively.
