Fort Worth, Texas,
05:21 PM

What Is Sickle Cell Disease?


Dr. Johnson with patient

Advanced Treatments and Research for Sickle Cell Disease

Dr. Clarissa Johnson, director of the Sickle Cell Program at Cook Childrens, talks about advanced treatments and therapies as well as promising new clinical research on the horizon for sickle cell disease. Her extensive knowledge and passion for treating patients with sickle cell disease is the driving force behind bringing relief to hundreds of patients at Cook Children’s. Click here to listen.

Sickle Cell Disease is the abnormal shaping of red blood cells. The red blood cells are shaped like crescents instead of circles. They don’t last long and they can get stuck in the blood vessels, which blocks the blood flow, often resulting in pain and organ damage.

Sickle cell disease is a group of inherited red blood disorders affecting an important protein in the red blood cell. This protein is called hemoglobin. Hemoglobin helps the red blood cell to carry oxygen to all the different parts of the body. In sickle cell disease, the body produces one or more abnormal types of hemoglobin. This means that the ability of the red blood cell to carry oxygen to all parts of the body is changed. Sickle Cell Disease is a lifelong illness that can result in serious health problems.

There are different forms of Sickle cell disease which are named depending on whether a person inherits a sickle cell trait from each parent or if the person inherits sickle cell trait from one parent and a different abnormal hemoglobin trait from the other parent. Some common types of sickle cell disease include SS disease also known as Sickle Cell Anemia, Sickle Hemoglobin C disease, and Sickle Beta Thalassemia.

Sickle cell disease affects about 70,000-80,000 people nationwide. People with this disorder have atypical hemoglobin molecules including hemoglobin S, which can distort red blood cells into a sickle shape, thus the name "sickle cell disease." Normal blood cells are smooth, round, flexible and shaped like the letter O so they flow easily through the veins. However, if your child has sickle cell disease, his blood cells can become stiff, sticky and shaped like the letter C, causing a variety of problems. The sickle cells can block veins, causing damage to organs, and can also cause mild to severe and sometimes excruciating pain for the patient. Sickle cells also have a shorter lifecycle, which results in anemia because the body cannot regenerate new cells fast enough.

Among the many misconceptions of SCD, African Americans are not the only race affected by the disease. While the African American race makes up a reported 60 to 80 percent of Americans diagnosed, people of Indian, Middle Eastern, Hispanic and Mediterranean descent may also be affected.

The cure for SCD lies in bone marrow transplants, and while siblings typically are the best matches for this disease, anyone willing to donate can be tested.

An estimated 3,000 people die each year in the United States from waiting for a donor for a bone marrow transplant because of the lack of donors on the registry.

Donating bone marrow requires less than 5 percent of bone marrow cells and is typically taken from the hip of the donor or through a non-surgical procedure in which it is collected through an IV.

"While Stem cell transplant can provide a cure for Sickle Cell Disease, it is not an easy cure. There can be many complications. Some patients may not engraft, meaning the donor cells may not grow, and the patient’s own cell grow back instead or a second transplant is needed," said Clarissa Johnson, M.D., medical director of the Sickle Cell Programt at Cook Children's. "There can also be challenges with finding a donor. So unfortunately we cannot consider stem cell transplant to be a universal cure that is available to all with the disease. More research for a universal cure is needed. There are small trials with gene therapy being done currently which I hope will prove successful to offer the chance of cure to even more people with Sickle Cell Disease.”

The Sickle Cell Program at Cook Children's Sickle Cell Center serves more than 400 children annually across northern Texas and adjoining states. The program offers testing, diagnosis and treatment for the many types of sickle cell disease. Research is also an important part of the program as the team seeks new ways to treat and prevent the many complications that can occur as a result of this disease. Click here to learn more.

Cook Children's Hematology and Oncology Center is actively involved in sickle cell disease research, including stem cell transplantation. The recognized team of researchers work with leading organizations across the U.S. and around the globe to find solutions to treating, preventing and curing the disease. As a research facility, Cook Children's also has a number of clinical trials available and we are able to match our patients to trials at other facilities. To learn more about the ongoing research at Cook Children's, click here.

Cook Children's Sickle Cell Center




Get to know Clarissa Johnson, M.D.

Clarissa Johnson, M.D., is the medical director of the Cook Children's Sickle Cell Center. At the core of Dr. Johnson's passion for m​edicine and pediatrics is her desire to be an advocate for those who don't have a voice for themselves. Her initial intere​​st was to be a research scientist, but her realization that face-to-face interaction with patients and their families might make a more direct difference in people's lives led her to pediatrics, and eventually to pediatric hematology and oncology.

Dr. Johnson's personal commitment to have a positive impact is made every day at Cook Children'​s. It has also led to her involvement in medical mission trips to hospitals and clinics in Nigeria, Ethiopia and Eritrea.

"I returned from those mission trips with more of an international view of health care. It furthered my advocacy for people who aren't able to speak for themselves," she says. This experience, combined with the fact that her parents instilled in her a multicultural outlook on the world, helps her in her medical practice right here in Ft. Worth, Texas. She recognizes that an indispensable asset in caring for patients and families is compassionate understanding​.

When she's not caring for patients, Dr. Johnson enjoys the performing arts including dance, concerts and Broadway theatre. Likewise, she can quickly turn the conversation to football, both professional and college ball, and often surprises her young patients with her passion for LSU footbal​l. Learn more about the Cook Children's Sickle Cell Center.

5 FACTS You Should Know About Sickle Cell Disease from the Centers for Disease Control and Prevention

1. A child gets sickle cell disease (SCD) when he or she receives two sickle cell genes - one from each parent. A child who inherits only one sickle cell gene has sickle cell trait (SCT). If both parents have either SCD or SCT, it's imoprtant for them to discuss this information with each other and with a doctor when making decisions about family planning.

2. SCD has many faces. The disease affects millions of people worldwide and is especially common among people who come from and whose ancestors come from the following regions highlighted in red.

3. SCD can be cured for certain patients. A bone marrow transplant, which involves collecting healthy cells from a donor's bone marrow transplant may not be the best choice for all paitents because it comes with serious risk. A bone marrow transplant expert can advise patients about whether or not it is a good choice for them.

4. Anemia is a common effect of SCD, but it can be treated. In someone with SCD, red blood cells die early and not enough are left to carry oxygen throughout the body, causing anemia, infection or enlargement of the spleen, an organ that stores red blood cells, may make anemia worse. Blood transfusioins are used to treat severe anemia.

5. A person with SCD can live a long and high quality life. More than 95 percent of newborns with SCD in the United State will live to be adults. People with SCD can lower their chance of difficulties from the diseae and enjoy many normal activies by:

  • Getting regular checkups with their doctor.
  • Following treatments prescribed by their doctor, such as taking medication called hyroxyurea.
  • Preventing infections by taking simple steps including washing their hands.
  • Practicing healthy habits like drinking 8 to 10 glasses of water per day and eating healthy food.
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