
Get Familiar: Het Sikkelcelfonds
Get Familiar: Het Sikkelcelfonds
Interview by Passion Dzenga and Liesje VerhaveAs part of our collaboration with the Dutch Sickle Cell Foundation, we spoke to Professor Marjon Cnossen, pediatric haematologist, researcher and one of the driving forces behind the foundation, to better understand the realities of sickle cell disease, why awareness remains so low, and why community-led support matters more than ever. From the outside, sickle cell disease is still widely misunderstood. For many families living with it, that lack of recognition can feel almost as difficult as the illness itself. Through research, advocacy, fundraising and events like the Bijlmer Run, the Sickle Cell Foundation is helping to change that — building not just visibility, but real support for patients and their families.Could you briefly explain what sickle cell disease is for people who may never have heard of it?Sickle cell disease is a hereditary blood disease that mainly affects people of colour, although that includes many different communities. Most patients have ancestors from Africa, but we also see a lot of patients from the Middle East and India. Those are also regions where the disease is very common.The disease developed through something that was originally protective. Thousands of years ago, a mutation in the DNA emerged that helped protect people against malaria, which is common in regions around the equator. If you carried that mutation, you were better protected against malaria, and because of that, many carriers lived longer and passed this genetic trait on to their children. Over time, more and more people became carriers. If two carriers have a child together, there is a one-in-four chance that the child will be born with sickle cell disease.In practical terms, sickle cell disease affects the red blood cells. Normally, they are round, but in sickle cell disease, they become crescent or moon-shaped. These cells can stick together and block the blood flow. Red blood cells carry oxygen, so when blood flow is blocked, parts of the body don’t get enough oxygen. That causes pain, and over time, it can also cause serious damage to organs.What does that mean for daily life?The impact is huge. Patients live with severe anaemia. A healthy person in the Netherlands might have a haemoglobin level around seven or eight, but many sickle cell patients have half of that — around three-and-a-half or four. That means they are tired all the time. They struggle to concentrate. They may not be able to participate in sports or activities like their peers.That’s one of the things I find emotional as a doctor. Sometimes people see these children and say they are lazy or not trying hard enough. But if your haemoglobin level is half of what it should be, of course, you are exhausted. There is a very real reason a child might fall asleep in class.Then there are the extremely painful episodes, called sickle cell crises. These can be triggered by very normal things: cold weather, changes in temperature, stress, fever, infection, dehydration, tiredness. In the Netherlands, that means winter can be especially difficult. Patients often live in anticipation of the next sickle cell crisis.When a severe crisis happens, they may need to come into the hospital for strong pain medication such as morphine, ketamine and other treatments. Sometimes they are admitted for one or even two weeks.And beyond that, there is progressive organ damage. Because blood flow is repeatedly blocked and oxygen supply is reduced, organs can slowly start to fail. We see complications in the kidneys, liver, heart and brain. Patients can have strokes or other very serious long-term consequences.So although it’s a blood disorder, it really affects the whole body.Exactly. It is a systemic disease. It not only affects the blood. It affects the whole life of a patient — physically, mentally and socially. And there is another part people often forget: loneliness. Sickle cell disease is often invisible. If someone has childhood cancer, people understand immediately that something is wrong. They may look visibly ill. But with sickle cell disease, a patient can look “fine” to the outside world, even while living with constant fatigue, recurring pain and serious complications. That invisibility means many people do not understand the disease, and patients often feel very alone.Is that lack of awareness one of the biggest problems?Yes, absolutely. That is one of the biggest issues. Sickle cell disease is not rare globally — around 300,000 babies are born with it every year, and there are millions of people affected worldwide — but in the Netherlands, it is still treated like a rare disease. And even among rare diseases, it receives far too little attention.I also treat haemophilia, and everybody knows what haemophilia is. That shows you something important: awareness is not only about how severe a disease is. It is also about who gets seen, who gets heard, and who has access to influential networks.Patients with sickle cell disease are often too unwell to advocate for themselves. Their families are often working very hard and may not have access to the kinds of systems or connections that help bring national attention. So the disease remains invisible in places where visibility matters.That is exactly why the Sickle Cell Foundation is so important. We want to create a voice for patients and families. We want to make sure sickle cell disease is recognised as the severe and progressive disease that it is.What does treatment look like right now?We provide what we call comprehensive care. Patients are seen regularly, at least twice a year and more often if needed. In childhood, they receive antibiotics because their spleen does not function properly, which means they are more vulnerable to severe infections.From around nine months of age, many children also start a medication called hydroxycarbamide. That can help increase the amount of fetal haemoglobin in the blood, which reduces complications by modifying disease symptoms, making the disease less severe.Some patients also need regular blood transfusions. In more severe cases, especially when there are major complications, we use chronic transfusion programmes or exchange transfusions, where sickle blood is removed and donor blood is given.At the moment, the only curative treatment is stem cell transplantation, which is the same as a bone marrow transplant. The idea is that you replace the patient’s bone marrow — which is producing the sickle cells — with healthy donor bone marrow.That sounds incredibly intense.It is. It can cure the disease, and I have many patients who have been cured this way, but it is also a risky procedure. To do it, you first have to destroy the patient’s own bone marrow with chemotherapy. That makes them very vulnerable. They can get severe infections. The donor bone marrow can also interact with the host (graft versus host disease), causing severe complications. There is also a small but real risk of death. So, although the intervention is very promising, there is also a lot that can be improved.The difficult thing with sickle cell disease is that, ideally, you want to do this treatment when children are still young — before organ damage becomes severe — because the outcomes are better. But at that point, the child is still relatively healthy. It is often very hard for families to decide to put a young child through such an impactful. We as doctors know the disease is progressive, but we cannot predict exactly how severely it will develop in each person. That makes decision-making very difficult.A major part of care also depends on blood and donor systems. Is donor diversity a big issue?Yes, very much so. We need more blood donors from diverse cultural backgrounds. That is incredibly important. The Dutch blood bank Sanquin is actively working on this now, because many of our patients have blood types or blood characteristics that are less common in the current donor pool. The more diverse the donor bank becomes, the better we can care for patients with sickle cell disease and thalassemia. Not everyone is in a position to donate blood regularly, of course, but if you can, it is a very meaningful way to help.So if people want to help in a tangible way, becoming a donor is one step. What else can they do?Talk about sickle cell disease. That is really one of the most important things. Talk about it if you know someone with the disease. Talk about it if you have learned something about it. Share information. Raise awareness. That really matters.People can also support the foundation directly, donate money, support collaborations like this wonderful Patta t-shirt project, and come to events like the Bijlmer Run. These moments are important not only for fundraising but also because they create visibility and community.For us, being in Bijlmer feels very special. Many of our patients and families live there. When we are present there, people already know what sickle cell disease is. They know someone who has it. They come to the stand and say, “I know what this is about.” That feels very different from having to explain it from scratch every time. It feels like coming home.What role does the foundation play beyond raising awareness?We support research, raise funds for better treatment and better care, and help give patients and families a stronger voice. For me personally, the foundation came from frustration. There was simply too little funding, too little awareness, and too little urgency around the disease. We founded the Sickle Cell Foundation in 2017 because we felt something had to change. We started small, but we are becoming more meaningful, and that makes me very hopeful.Are there any key moments this year that people should look out for?Yes! World Sickle Cell Day on the 19th of June is very important. This year, we are organising an event in ITA in Amsterdam for scientists and of course, also for patients! I hope that in the future this event will bring more and more patients together from across the Netherlands. We are growing as a foundation. There is more programming coming. Patients are organising things too. Our new director, Inge, is fantastic. There is a real sense that the foundation is building momentum.Finally, if someone remembers one thing from this conversation, what would you want it to be?Sickle cell disease is serious. It is progressive. It is painful. And it deserves much more awareness than it currently receives. And also: talk about it. Support where you can. Whether that means donating blood, supporting the foundation, buying the t-shirt, coming to the Bijlmer Run, or simply helping spread the word, it all matters. These kinds of collaborations, as we have with the wonderful Team Bijlmer Run and Team Patta, are so powerful because they feel organic. They feel logical. They come from people recognising a shared purpose. And those are always the strongest collaborations.Patta x nijntje T-Shirt available Saturday, May 16th, exclusively at the Bijmer Run.














