An expert in sickle cell disease provides an overview of sickle cell disease and the ultimate burden that it has on patients.
Ifeyinwa Osunkwo, MD, MPH: Dr Smith, as an expert in sickle cell disease, can you describe what sickle cell disease is? How does it manifest in individuals like Jamaal?
Wally Smith, MD: Sickle cell disease has been called the first molecular disease. It results from an alteration in the DNA. There’s 1 little protein substitution in the DNA that causes a change in the proteins that make up this oxygen-carrying molecule called hemoglobin. When the hemoglobin doesn’t hold on to oxygen, because it’s not shaped in the same way in sickle cell disease, the shapes allow hemoglobin to link up into almost fibers that stretch the cell—which is normally a doughnut shape—into abnormal shapes, including this sickle shape. People don’t know about the farmer’s sickle, but think about a crescent moon. You can almost call it crescent moon disease because that’s the way the cells are shaped.
You would think that would be bad enough in and of itself, but sickle cell disease affects every place that requires oxygen in the whole body—every organ, every tissue. There’s devastating pain. There’s early death due to infection, because your spleen is an organ that helps get rid of infection and it goes to pot. The gallbladder is affected. The brain is affected. You can have strokes. The lung is affected. You can have pneumonia from infection. You can have destruction of the lung. The kidneys are affected. In Jamaal’s case, his kidney was destroyed. He actually had to have a kidney transplant. Your legs, bones, and muscles can be affected. Every place in your body that can be affected with sickle cell disease is usually affected by oxygen deprivation and cell death.
It’s very common, certainly in sub-Saharan Africa. Even in the United States, we may currently have 100,000 patients with it. One of 12 Black people are probably carrying sickle cell trait. Jamaal’s mom was talking about herself. She’s a patient. She’s not just a carrier. Jamaal, his brother, and Sherry all suffer with this disease. It’s the most commonly inherited hemoglobinopathy we have and 1 of the most common rare diseases. Rare diseases are those that affect fewer than 200,000 people in the United States. It’s 1 of the most common rare diseases.
Ifeyinwa Osunkwo, MD, MPH: That’s interesting that you can use common and rare in the same sentence. It explains why we’re doing this webinar: to raise awareness about how much this disease impacts individual people, even though it may be considered a rare disease.
Can you tell us a little about the burden? You said that when somebody has sickle cell disease, it impacts every organ. Give us an example of how it presents in patients you see in clinic.
Wally Smith, MD: The most common presentation is pain. The pain is called vaso-occlusive crisis. Let’s break that word down. Vaso-occlusive means that the blood vessels are blocked by these crescent moon-shaped cells that will not navigate through the small blood vessels. The pain is disabling. You have to go to the hospital. You have to get narcotics for it. You’re doubled over in pain. You’d like a gun to end your life. It’s that bad. It can go on for days. By the time you’re 20 or 25 years of age, about half of adults have pain every day. Whether it’s a vaso-occlusive crisis is up for debate, but they’re having pain all the time. That’s by far the most common presentation.
In childhood, the infections we’re talking about can take your life. I’m talking about anything that would require your spleen to work. Those infections tend to come from organisms like the pneumococcus. You’re going to possibly die from pneumonia, meningitis, or even overwhelming blood infection as a child, unless you’re given penicillin, which Jamaal referenced he got.
Ifeyinwa Osunkwo, MD, MPH: Some of these complications you mentioned are acute and lead you to go to the hospital. Others are chronic. Can you talk a little about the chronic complications that may not be pain? Sometimes people think, “You don’t have a lot of pain. You don’t have sickle cell problems.” What are the nonpainful but chronic complications of sickle cell disease?
Wally Smith, MD: There’s no such thing as a mildly affected sickle cell patient. Every patient with sickle cell disease is slowly destroying their cells. Whether they feel it or not, they’re destroying their cells. And it’s not them; the disease is destroying their cells. Every organ in the body could be destroyed. Let’s start with the brain. You could have brain destruction, so-called silent ischemia. You’re not going to feel that. You might test abnormally on your IQ tests or other developmental tests. That might be the way you’d pick it up. You might see it on an x-ray, even though you’ve never had an overt stroke.
It can affect your eyes. It can affect your retina. You start to have disease of the retina. It can affect your hearing. It can affect your heart. It can affect your pituitary gland, where you don’t mature sexually the way you should, or you have hormonal imbalance. Your lungs and kidneys, as I mentioned, can be affected. These all take time to develop. Fortunately, children don’t get all these complications at once. Think of it as early aging. Think of it as someone who might be 30 years of age, but they’ve got the body of a 60-year-old because of sickle cell disease that has been chewing away at all their organs.
Ifeyinwa Osunkwo, MD, MPH: Wow. That’s pretty profound: early aging because of the damage the sickle cells cause to different organs in the body. How do you diagnose sickle cell disease? How does somebody even know that they or their child have sickle cell disease?
Wally Smith, MD: In the late 1960s, we were able to come up with a very fancy test: hemoglobin electrophoresis. Before that, we had something called the Sickledex. It was a solubility test that told you if the gene was present or if sickle hemoglobin was present, but you didn’t know whether you had full-blown sickle cell disease or sickle cell trait. That’s all gone now. The way we diagnose it is with the hemoglobin electrophoresis. Fortunately, every state in the United States does that on every baby born. Newborn screening programs to detect sickle cell disease pick it up at birth, and we immediately know whether the patient has sickle cell disease at birth. That information is given to the parents and is hopefully kept by them. Even if the patient has sickle cell trait, that information is given to the parents so they can pass it along.
Ifeyinwa Osunkwo, MD, MPH: That’s very important. With newborn screening, we’re able to detect people with sickle cell disease at birth. So if you have sickle cell trait, you’re aware of your status as you get older. And the parents are supposed to translate that information to the child.
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Transcript Edited for Clarity