Prof. Dr. med. Friedrich Trefz received his medical degree from the University of Heidelberg in 1972. After receiving his degree he had a training in the biochemical laboratory at the Childrens Hospital in Heidelberg, and in 1975 he started his training in pediatrics under Prof.Dr. Horst Bickel. In 1983 he received his degree in Paediatrics, in 1985 he became the head of the “Sektion Pädiatrische Stoffwechselkrankeheiten” at the University Children’s Hospital of Heidelberg. Later in 2009 he received an additional degree in Paediatric Diabetes and Endocrinology.

Prof. Dr. med. Trefz has received many grants from the German Federal Ministry of Education and Research, from 1994-2002 he was pricipal investigator of the International Maternal PKU study together with Prof. Richard Koch (Los Angeles), and Prof. Harvey Levy (Boston). He also was principal German investigator in the International Sapropterin Study from 2005 to 2007.

In 1992 he moved from Heidelberg to Reutlingen and became the head of the department of pediatrics at the Klinik für Kinder und Jugendmedizin at Klinikum am Steinenberg, Reutlingen, School of Medicine, University of Tuebingen. In 2010 he retired from the Childrens Hospital in Reutlingen and became head of the outpatient medical centre for Women, Children and Adolescents , Kreiskliniken Reutlingen, in Gammertingen, Germany. In 4/2015 he went back to the University Clinic of Heidelberg and established under the supervision of Prof. Dr. Georg Hoffmann and Prof. Dr. Peter Nawroth the adult outpatient clinic for rare metabolic disorders (up to 12/2017).

In 2018 he founded a private company for “Metabolic Consulting and Research” to further support knowledge and research in inborn errors of metabolism. He has more than 45 years of experience especially in treatment of patients with phenylketonuria.