Specialist in Endocrinology - Andrology - Diabetology. Special interest in transgender health. Guy G. R. T’Sjoen was born on July 26th, 1970 in Oudenaarde, Belgium. His medical degree was obtained at the Ghent University (cum laude) in 1995. From 1995 till 2000 he specialised in Internal Medicine (St.- Jan Ziekenhuis, Brugge, St.- Bartholomew’s, London; Ghent University Hospital). He obtained his specialist qualifications in Endocrinology- Diabetology in 2001. He obtained the title of Clinical Andrologist from the European Academy of Andrology in 2002 (Malmö, Sweden) and Fellow of the European Committee on Sexual Medicine (FECSM, Istanbul 2014). Currently he is working as head of department, clinical staff physician and clinical researcher at the Department of Endocrinology including the Center for Sexology and Gender, and the Center for Andrology (certified by the European Academy of Andrology) at the Ghent University Hospital, Belgium. He is author of the Dutch books 'Transgenderzorg' (ACCO) 'Onder de gordel' and ‘Hormonen onder controle’ (Van Halewyck) ‘Het Transgender Boek’ (Angèle) and co-editor of 'Gender Dysphoria and Gender Incongruence', published by Routledge. He was (interim) president of EPATH (European Professional Association for Transgender Health) since 2015, and past-president since august 2021. He publishes on androgen deficiency, transgender health, pituitary disease, sexual health and variations of sexual differentiation. Memberships include the Endocrine Society, the Belgian Endocrine Society (board member- secretary), the Gender team and the DSD team of the Ghent University Hospital, The World Professional Association for Transgender Health (scientific committee) and The European Society for Sexual Medicine. He is co-editor of the Journal of Sexual Medicine and the International Journal of Transgender Health. He organized the first four conferences for EPATH (Gent, 2015; Belgrade, 2017; Rome, 2019; Gothenburg, 2021). His research line was covered in Nature (2019) and The Lancet Diabetes and Endocrinology (2020).