Patient education: Sickle cell trait (The Basics)

What is sickle cell trait? — Sickle cell trait is a condition that is passed on in families. It happens when you get the abnormal sickle cell gene from one of your parents and a normal gene from the other parent. Sickle cell trait is not a disease. Most people with sickle cell trait never have any symptoms. But there are some rare things you should know about.

People with sickle cell trait can pass the abnormal gene to their children too. A child might get the abnormal gene or might not. If the child gets the gene, they could have sickle cell trait or sickle cell disease, depending on what gene they get from the other parent (figure 1).

The sickle cell gene is more common in people with ancestors from certain parts of the world. It is most common in people from countries in Africa, the Middle East, India, South America, or the Mediterranean area.

What is sickle cell disease? — Sickle cell disease is a disease that can cause pain and many other medical problems. There are a few different forms of sickle cell disease. People who got the sickle cell gene from both parents have something called "sickle cell anemia." It's also possible to get the sickle cell gene from one parent and a different abnormal gene from the other parent. One example of this is called "sickle beta thalassemia." All forms of sickle cell disease affect a protein called hemoglobin, which is found inside red blood cells. Hemoglobin's job is to carry oxygen to the body's tissues.

Red blood cells that have normal hemoglobin can easily move through all of the blood vessels. Red blood cells in people who have sickle cell disease are shaped abnormally, like a crescent or an old-time tool called a "sickle" (figure 2). The abnormal red blood cells do not move through blood vessels easily, and so they don't bring enough oxygen to the body's organs.

What are the symptoms of sickle cell trait? — Sickle cell trait usually doesn't cause any symptoms at all. The only way most people know they have sickle cell trait is if they have a blood test for it. Even though it is not a disease, under certain conditions sickle cell trait can cause some problems, including:

●Blood in the urine

●Kidney cancer (in very rare cases)

●Blood clots, especially under extreme conditions, such as when climbing high mountains or when scuba diving

●Higher chance of problems from certain eye injuries

●Higher chance of problems affecting an organ called the spleen

Is there a test for sickle cell trait? — Yes, there is a blood test that can show if a person has sickle cell trait. In the United States, all newborn babies are tested for the sickle cell gene before they leave the hospital. This test can also show sickle cell trait, but parents are not always told if their child has sickle cell trait.

Doctors test for sickle cell trait in:

●People who have sickle cell disease in the family, especially if they are planning to have a baby – This helps them find out how likely it is that their child will have sickle cell anemia or sickle cell trait.

●Adults or teens with symptoms that could be related to sickle cell trait or sickle cell disease – Symptoms include certain types of pain, blood in the urine, long-lasting erections, blood clots, or unexplained bleeding in the eye.

Military and sports organizations have their own rules about testing for sickle cell trait.

Is there anything I should do on my own? — Yes. If you have sickle cell trait, be careful when you exercise intensely or for a long time. Make sure you drink enough fluids, do not get too overheated, and pay attention to any symptoms you might develop.

Some people believe that having sickle cell trait makes a person more likely to have rare, serious medical problems during intense exercise. The risk for people with sickle cell trait is being studied and is not something all experts agree on. Whether or not people with sickle cell trait are at increased risk, all people should drink enough and try to stay cool when they exercise.

What if I want to have children? — If you want to have children, talk with your doctor. Your doctor might recommend that you be tested for sickle cell trait. You might also see a genetic counselor. Genetic counselors are experts at helping people understand health problems that run in families.

Your doctor or a genetic counselor can tell you your baby's chance of having sickle cell disease or sickle cell trait, and whether your partner will need to be tested.

More on this topic

Patient education: When your child has sickle cell disease (The Basics)
Patient education: Sickle cell disease (The Basics)