Undiagnosed diseases do not stop at borders, and neither does our work. What began in 1999 with one Swedish family's determination is today a worldwide collaboration — from Stockholm and Nijmegen to Rochester, Hyderabad and Singapore.

At the heart of it is the Undiagnosed Hackathon, pioneered and driven by Wilhelm Foundation. Clinicians, geneticists, bioinformaticians and data scientists work side by side around individual families — no hierarchy, no silos. Every hackathon has brought answers to families who waited years, and each teaches us something new about the roughly 60 percent of undiagnosed diseases we still cannot solve.

Around it grows one Wilhelm Foundation ecosystem: the Hugo Fellows Program, investing in early-career specialists; Emma's Playground, where collaboration continues between our meetings; and Global Undiagnosed Day on 29 April. As co-founder of Undiagnosed Diseases Network International, we work so that knowledge and technology reach families everywhere — including where a diagnosis is still out of reach.

A late diagnosis can have irreversible consequences and, in the worst case, be fatal. Diagnosis changes everything.

To every colleague, host institution and family who walks with us: thank you. Together we make the invisible visible.