As the current UDN transitions to a new sustainable program for undiagnosed diseases, the NIH UDN Program Working Group wants to take this opportunity to thank the UDN participants. We appreciate that patients and families have traveled a difficult journey to participate in the UDN. From countless heroic stories, we have been made aware of just how much time, effort, family sacrifice, dedication, and emotional angst it took for each and every UDN visit. Their participation has given immeasurable gifts to the world including heightened awareness of rare diseases in medical, research, government and industrial communities. The clinical information and research samples they shared have synergized with others, through the UDN Coordinating Center, to optimize opportunities for their diagnosis and care and built the path for those whose journey is in future. We are grateful to all who have participated in the UDN, their families and their medical teams.