Result First National Undiagnosed Hackathon: diagnoses for five families Close collaboration Dutch university medical centers successful

19 May 2026

The first edition of the National Undiagnosed Hackathon, held on 23 and 24 April at Radboudumc in Nijmegen, has been successfully completed. With over 140 participants from various disciplines across the seven university medical centers in the Netherlands, 33 families searching for a diagnosis, a visit from Queen Máxima, and diagnoses for 5 families, the teams look back on a remarkable event — the first of hopefully many under the UMCNL banner.

On 23 April, the organization officially kicked off the Hackathon, and participants were introduced to five families from the Southeast Netherlands region. After the introductions, they began their search for diagnoses for a total of 33 families. During this first day, Queen Máxima visited the Hackathon, adding a festive touch to the inaugural edition. She spoke with families and participants and visited the photo exhibition featuring portraits of patients without a diagnosis. Three diagnoses were found on this first day. On day two, the teams continued their investigations, and the horn sounded two more times for newly identified diagnoses.

After 48 hours, the teams not only celebrated the five confirmed diagnoses but also identified strong indications pointing toward diagnoses for eight additional families. However, further research beyond the Hackathon is required. The families have since been informed after the necessary double-checks.

Multidisciplinary teams

Participants were divided into five teams, each composed of members from all seven participating university medical centers and assembled in a multidisciplinary way: clinical geneticists, medical specialists, laboratory specialists in clinical genetics, researchers, data analysts, bioinformaticians, and AI experts. Each team was assigned several families to investigate. An additional team consisted of technology experts who could be consulted for technical expertise. For this first Hackathon, the teams were given Dutch names: Tulp (Tulip), Molen (Windmill), Fiets (Bicycle), Klomp (Clog), and Kaas (Cheese).

For many participants, such as laboratory specialists and bioinformaticians, who normally have no direct contact with patients, meeting the families made a deep impression. It provided extra motivation for this driven group to find diagnoses within 48 hours. They could not wait to begin.

Success

Halfway through the first day, cheers erupted when Team Tulp sounded the horn. After just a few hours of comparing, testing, analyzing, reviewing files, and double-checking, they had found the first diagnosis. Others rushed over at the sound of the horn and saw the joy on the participants’ faces. Across all teams, at least one diagnosis or strong suspicion of a diagnosis was found during the two days — 13 in total. 

“All these families have been waiting for years to hear the liberating words: ‘We have found a diagnosis for your condition.’ A diagnosis offers perspective for the future, better guidance and treatment, and a less uncertain outlook,” says Wendy van Zelst, professor and head of the Department of Genetics at Radboudumc.

Why a diagnosis matters

A diagnosis helps ensure that patients receive the right care and guidance while preventing incorrect treatments. It also helps families explain to others what is going on (with their child) and makes it easier to access appropriate support and resources. A diagnosis reduces uncertainty for patients and parents, can prevent or relieve feelings of guilt, and provides opportunities for connecting with peers. It also often offers more clarity about the prognosis and what it means for potential future children.

Collective brainpower

What made this gathering so unique and successful was the overwhelming sense of solidarity and collaboration; the spirit and combined expertise within and between teams were impressive — true “crowd intelligence.” In the weeks leading up to the event, the organizing genetics team at Radboudumc worked intensively. Using the latest technologies, new data for the 33 families were generated in record time. In 2025, a breakthrough in this type of research was achieved. Read more about it here: World first: Radboudumc pioneers new genetic test in clinical practice.

Van Zelst looks back with great satisfaction on this first National Undiagnosed Hackathon: “After my experience with the international hackathon in 2024, I saw many opportunities to bring this to the Netherlands as well — together with colleagues from the other university medical centers. There is enough expertise in the Netherlands to make this possible, and this event proves it. Together, we created something meaningful for our patients and their families. This is the first of hopefully many. How wonderful it would be if we could help many more families finally receive the long-awaited diagnosis.”

Clinical geneticist Emilia Bijlsma from Leiden University Medical Center (LUMC), one of the participants, reflects: “When you start, you don’t know exactly what to expect. We do this ‘detective work’ together, and the direct contact with lab specialists and clinical geneticists is incredibly stimulating and valuable. I was deeply immersed in the investigation myself; and suddenly I realized that if something comes out of this, it would mean the world to patients. And it wasn’t just the patient — the emotion that filled the room when something was truly found - is indescribable. Suddenly there is an answer — clear and definitive. What follows is an overwhelming feeling. Being able to share that with your own patient and their family is beyond words.”

Partners

The National Hackathon is a joint project of all university medical centers in the Netherlands and UMCNL. This first edition was organized and funded within the Joint Action on Integration of ERNs into National Healthcare Systems (JARDIN Joint Action). 

Queen Máxima meet the families.

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