Hans-Jurgen Mager has been involved in HHT care and research for more than 20 years. He was co-author of more than 80 articles on HHT in peer-reviewed medical journals over the last 24 years. He is head of the HHT center of the St. Antonius Hospital, in Nieuwegein, which is the only (official) HHT center in the Netherlands. Currently, more than 1600 patients with a definite diagnosis of HHT are under control or treatment in the St. Antonius Hospital. Together with his colleagues Marco Post en Sanne Boerman, he represents the St. Antonius Hospital within the HHT working group of VASCERN, the European Reference Network for rare vascular diseases. Since 2019 Hans-Jurgen Mager is chairman of the Global Research and Medical Advisory Board of Cure HHT. He was co-chair of the committee who made new guidelines for HHT, that were published in 2020.
He is guest-editor of the HHT special topical collection of the Journal of Clinical Medicine, together with Marco Post and Carmelo Bernabeu. Since 2020 he is a member of the Scientific Advisory Board of Vaderis, a Swiss biotechnology company, focusing on treatment of rare diseases caused by vascular malformations and aiming to be the first in the world to provide a medicine for HHT; he is coordinating investigator for the international phase IB study that started recently.