WHAT IS SICKLE CELL?

What is Sickle Cell?

Sickle cell disorder affects many families. In fact, approximately one in every 365 African American children and one in every 16,300 Hispanic-American children will be diagnosed with sickle cell disorder, making it the most commonly diagnosed disorder in newborn screenings. People with sickle cell disorder have red blood cells that contain mostly hemoglobin* S, an abnormal type of hemoglobin. Sometimes these red blood cells become sickle-shaped (crescent shaped) and have difficulty passing through small blood vessels.

Medical Problems

Sickle cells are destroyed rapidly in the body of people with the disorder causing anemia, jaundice and the formation of gallstones.

The sickle cells also block the flow of blood through vessels resulting in lung tissue damage (acute chest syndrome), pain episodes (arms, legs, chest and abdomen), stroke and priapism (painful prolonged erection). It also causes damage to most organs including the spleen, kidneys and liver. Damage to the spleen makes sickle cell disorder patients, especially young children, easily overwhelmed by certain bacterial infections.

Treatment

Health maintenance for patients with sickle cell disorder starts with early diagnosis, preferably in the newborn period and includes penicillin prophylaxis, vaccination against pneumococcus bacteria and folic acid supplementation.

Treatment of complications often includes antibiotics, pain management, intravenous fluids, blood transfusion and surgery all backed by psycho-social support. Like all patients with chronic disorder patients are best managed in a comprehensive multi-disciplinary program of care. Blood transfusions help benefit sickle cell disorder patients by reducing recurrent pain crises, risk of stroke and other complications.

Because red blood cells contain iron, and there is no natural way for the body to eliminate it, patients who receive repeated blood transfusions can accumulate iron in the body until it reaches toxic levels. It is important to remove excess iron from the body, because it can gather in the heart, liver, and other organs and may lead to organ damage. Treatments are available to eliminate iron overload.

The National Human Genome Research Institute

A baby born with sickle cell disorder inherits a gene for the disorder from both parents. When both parents have the genetic defect, there's a 25 percent chance that each child will be born with sickle cell disorder.

If a child inherits only one copy of the defective gene (from either parent), there is a 50 percent chance that the child will carry the sickle cell trait. People who only carry the sickle cell trait typically don't get the disorder, but can pass the defective gene onto their children.

What is a Sickle Cell Trait?

Sickle Cell Disorder Association of America

Sickle Cell trait (AS) is an inherited condition in which both hemoglobin A and S are produced in the red blood cells, always more A than S. Sickle cell trait is not a type of sickle cell disorder. People with sickle cell trait are generally healthy.

Inheritance

Sickle cell conditions are inherited from parents in much the same way as blood type, hair color and texture, eye color and other physical traits. The types of hemoglobin a person makes in the red blood cells depend upon what hemoglobin genes the person inherits from his or her parents. Like most genes, hemoglobin genes are inherited in two sets of one from each parent.

How Can I get tested for Sickle Cell?

Doctors diagnose sickle cell through a blood test that checks for hemoglobin S - the defective form of hemoglobin. To confirm the diagnosis, a sample of blood is examined under a microscope to check for large numbers of sickled red blood cells - the hallmark trait of the disorder.

In more than 40 states, testing for the defective sickle cell gene is routinely performed on newborns.

Sickle cell disorder can also be detected in an unborn baby. Amniocentesis, a procedure in which a needle is used to take fluid from around the baby for testing, can show whether the fetus has sickle cell disorder or carries the sickle cell gene. If the test shows that the child will have sickle cell disorder, some parents may choose not to continue the pregnancy. Genetic counselors can help parents make these difficult decisions.

A new technique used in conjunction with in vitro fertilization, called pre-implantation genetic diagnosis (PGD), enables parents who carry the sickle cell trait to test embryos for the defective gene before implantation, and to choose to implant only those embryos free of the sickle cell gene.

-National Genome Research Institute